Country：Japan

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Country：Japan

受賞題目：「疎水性高分子の単分子膜形成手法の開発と分子組織化への展開」

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Country：Japan

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Country：Japan

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Publishing type：Research paper (scientific journal)   Publisher：Wiley  

Abstract

Material‐networked conduction paths provide nonlinear electronic properties, which are essential components of computing and physically mimic the brain. In this study, the formation of conjugated polymer monolayer networks and their nonlinear charge transport is demonstrated. Poly(3‐hexylthiophene) (P3HT) monolayer networks doped with 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4TCNQ) is fabricated using the co‐spread method with an amphiphilic liquid crystal molecule at the air–water interface. Atomic force microscopy and Ultraviolet–visible–near‐infrared absorption spectroscopy measurements reveal the network surface morphologies and doped electronic states. The correlation between the nonlinear electronic characteristics and network structures of the P3HT/F4TCNQ monolayer networks is further systematically investigated through current–voltage and voltage–time measurements for various doping levels, network densities, and numbers of transferred layers. The current–voltage characteristics of the P3HT/F4TCNQ monolayer network device with a simple two‐terminal structure exhibit nonlinear and ohmic conduction behavior, which depend strongly on the network density and geometric dimension (number of transferred layers). It is concluded that the nonlinear properties arise from the limited and unique network of 2D conduction passes. This study highlights the unique features of conducting polymer monolayer networks, paving the way for neuromorphic device applications including conjugated semiconducting polymer‐based material reservoirs with controllable nanostructures.

DOI： 10.1002/aelm.202400427

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Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acs.jpcb.4c03123

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Publishing type：Research paper (scientific journal)   Publisher：Wiley  

Abstract

Nanofluidic ionic diodes have attracted much attention due to their unique functions as unidirectional ion transportation ability and promising applications from molecular sensing, and energy harvesting to emerging neuromorphic devices. However, it remains a challenge to fabricate diode‐like nanofluidic systems with ultrathin film thickness <100 nm. Herein the formation of ultrathin ionic diodes from hybrid nanoassemblies of nanoporous (NP) SiO₂ nanofilms and polyelectrolyte layer‐by‐layer (LbL) multilayers is described. Ultrathin ionic diodes are prepared by integrating polyelectrolyte multilayers onto photo‐oxidized NP SiO₂ nanofilms obtained from silsesquioxane‐containing block copolymer thin films as a template. The obtained ultrathin ionic diodes exhibit ion current rectification (ICR) properties with high ICR factor = ≈20 under low ionic strength and asymmetric pH conditions. It is concluded that this ICR behavior arises from effective ion accumulation and depletion at the interface of NP SiO₂ nanofilms and LbL multilayers attributed to high ion selectivity by combining the experimental data and theoretical calculations using finite element methods. These results demonstrate that the hybrid nano assemblies of NP SiO₂ nanofilms and polyelectrolyte LbL multilayers have potential applications for (bio)sensing materials and integrated ionic circuits for seamless connection of human‐machine interfaces.

DOI： 10.1002/smll.202404306

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Publishing type：Research paper (scientific journal)  

DOI： 10.1021/acs.langmuir.4c01168

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Publishing type：Research paper (scientific journal)  

DOI： 10.1021/ACS.INORGCHEM.3C04526

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Publishing type：Research paper (scientific journal)  

DOI： 10.1021/ACS.JPCC.3C06848

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Language：English   Publishing type：Research paper (scientific journal)  

Films that exhibit different metallic luster on the front and back, called Janus metallic films, have broad applications ranging from design materials to optical devices. However, the fabrication of these films is often a complicated process involving multiple metal deposition steps, thermal annealing, and calcination. Herein, we report the simple preparation of a Janus metallic film by electroless deposition of silver on a poly(dopamine acrylamide) (pDOPAm) thin film. pDOPAm was successfully synthesized via the controlled reversible addition-fragmentation chain transfer polymerization of dopamine acrylamide without a protective group using dimethylformamide as the solvent. The synthesized pDOPAm was spin-coated onto a solid substrate, which was then immersed in an aqueous AgNO3 solution to achieve the electroless deposition of silver. Our preparation method will considerably simplify the fabrication of Janus metallic films, enabling their widespread application as decorative or authentication materials.

DOI： 10.1039/d3ra05099h

PubMed

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Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acs.langmuir.3c01146

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Publishing type：Research paper (scientific journal)  

DOI： 10.3390/CRYST13020326

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Publishing type：Research paper (scientific journal)  

DOI： 10.1039/D3SM00265A

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Publishing type：Research paper (scientific journal)  

DOI： 10.1021/ACSOMEGA.2C06398

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Publishing type：Research paper (scientific journal)  

DOI： 10.1021/ACS.LANGMUIR.2C02950

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Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1002/marc.202200761

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Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/marc.202200761

Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acsami.2c13516

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Publishing type：Research paper (scientific journal)  

DOI： 10.2115/FIBERST.2022-0021

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Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

The mesogen orientations of liquid crystals are sensitive to the nature of the contacting surface. For side chain liquid crystalline polymer (SCLCP) films, most investigations have been conducted for thin films formed on a solid substrate surface such as glass, quartz and metal oxides, and little knowledge has been accumulated for SCLCP films whose top surface is covered by amorphous polymers. This work presents the effect of a topcoat with amorphous polymers placed on SCLCP films on the mesogen orientation and photoalignment behavior. When an SCLCP film that adopts a homeotropic mesogen orientation is covered with a glass plate or polymer layer, the mesogens turns to a random planar orientation. This planar orientation is favorable for efficient in-plane photoalignment by irradiation with linear polarized light. An in-plane order parameter exceeding 0.5 is readily obtained. Unexpectedly, a significant stabilization of the liquid crystal phase by over 10 °C is observed above the isotropization temperature of the SCLCP. These fundamental sets of knowledge should be significant in the fabrication of various polymer LC devices.

DOI： 10.3390/app12199410

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Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acsapm.2c00811

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Publishing type：Research paper (scientific journal)  

DOI： 10.1021/ACS.MACROMOL.2C00404

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Publishing type：Research paper (scientific journal)  

DOI： 10.1246/BCSJ.20210391

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Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acs.chemmater.1c03533

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Publishing type：Research paper (scientific journal)  

DOI： 10.1016/J.ORGEL.2021.106335

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Publishing type：Research paper (scientific journal)  

DOI： 10.1021/JACS.1C12652

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Publishing type：Research paper (scientific journal)  

DOI： 10.26434/CHEMRXIV-2022-PMSTK

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry ({RSC})  

Molecular glasses are low-molecular-weight organic compounds that are stable in the amorphous state at room temperature. Herein, we report a state- and water repellency-controllable molecular glass by n-alkane guest vapors. We observed that a macrocyclic host compound pillar[5]arene with the C2F5 fluoroalkyl groups changes from the crystalline to the amorphous state (molecular glass) by heating above its melting point and then cooling to room temperature. The pillar[5]arene molecular glass shows reversible transitions between amorphous and crystalline states by uptake and release of the n-alkane guest vapors, respectively. Furthermore, the n-alkane guest vapor-induced reversible changes in the water contact angle were also observed: water contact angles increased and then reverted back to the original state by the uptake and release of the n-alkane guest vapors, respectively, along with the changes in the chemical structure and roughness on the surface of the molecular glass. The water repellency of the molecular glass could be controlled by tuning the uptake ratio of the n-alkane guest vapor.

DOI： 10.1039/D2SC00828A

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Language：English   Publishing type：Research paper (scientific journal)  

Polysiloxanes are ubiquitous materials in industry and daily life derived from silicates, an abundant resource. They exhibit various properties, which depend on the main-chain network structure. Linear (1D backbone) polysiloxanes provide amorphous materials. They are recognized as fluid materials in the form of grease or oil with a low glass transition temperature. Herein we report that a simple linear polysiloxane, poly(3-aminopropylmethylsiloxane) hydrochloride, shows an elastic modulus comparable to that of stiff resins such as poly(tetrafluoroethylene). By introducing an ammonium salt at all the units of this polysiloxane, inter- and intramolecular ionic aggregates form, immensely enhancing the elastic modulus. This polysiloxane is highly hygroscopic, and its modulus can be altered reversibly 100 million times between moist and dry atmospheres. In addition, it works as a good adhesive for glass substrates with a shear strength of more than 1 MPa in the dry state. Despite its simple structure with a flexible backbone, this polymer unexpectedly self-assembles to form an ordered lamellar nanostructure in dry conditions. Consequently, this work reveals new functions and possibilities for polysiloxanes materials by densely introducing ionic groups.

DOI： 10.1038/s41598-021-97204-8

PubMed

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Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society ({ACS})  

DOI： 10.1021/ACSNANO.1C06975

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Publishing type：Research paper (scientific journal)   Publisher：Informa {UK} Limited  

DOI： 10.1080/15421406.2021.1946966

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Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acssuschemeng.1c01922

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Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1002/aelm.202100313

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Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/aelm.202100313

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY  

Molecular orientation, molecular packing structure, and electrical properties of thermally stable phthalocyanine, tert-butylated phthalocyanine (t-BuPcH2) in the thin film fabricated by bar-coating method were investigated. The XRD patterns indicated that the columns composed of t-BuPcH2 molecules formed hexagonal structure, the axis of which was parallel to the bar-sweep direction, and t-BuPcH2 molecules were vertically aligned to the bar-sweep direction. Uniaxially oriented thin films of t-BuPcH2 were successfully fabricated on Si substrate covered with polyimide by bar-coating method, and the field effect mobility of t-BuPcH2 was estimated to be 1.32 x 10(-4) cm(2) V-1 s(-1) at maximum. The field effect mobility parallel to the bar-sweep direction was approximately three times higher than that perpendicular to the bar-sweep direction due to high electrical conduction along the column axis of t-BuPcH2.

DOI： 10.1002/ECJ.12297

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Large mass transport driven by the difference in the photoisomerization-induced surface tension was demonstrated in ion pairs of anionic azobenzene and a cationic polymer. This material motion enabled fluorescence patterning using a trace amount of photoisomerized azobenzenes in complex form with a pi-electronic system.

DOI： 10.1039/d0cc07640f

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Taylor and Francis Ltd.  

Molecular-organized structures of polymer electrolytes have been extensively studied in recent years. Recently, we demonstrated that alkyl-sulfonated polyimide (ASPI) forms a lyotropic lamellar liquid crystalline (LC) phase under humid conditions and exhibits a high proton conductivity of 10−1 S cm−1 in the in-plane lamella direction at 95% relative humidity. In this work, we conducted precise structural evaluations of the lyotropic LC ASPI for in-plane aligned films prepared by a bar-coating method with a concentrated solution. The ASPI concentrated solution exhibited a birefringent feature and lyotropic LC properties. Humidity-controlled in situ polarized infrared spectroscopy confirmed the in-plane anisotropic structure of the aligned film with clear dichroism, and the dichroism did not change under humidification. Humidity-controlled in situ grazing-incidence X-ray scattering measurement revealed the hierarchical LC structure with main-chain smectic ordering in the lyotropic lamella structure of the shear aligned ASPI film.

DOI： 10.1080/15421406.2021.1946963

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Publishing type：Research paper (scientific journal)   Publisher：Wiley  

Honeycomb-patterned polymer films prepared by the breath figure method exhibit unique shape features. These films have potential in various applications, but functional materials are rarely embedded into the arrayed cavity. Here, a photoswitchable function of a compartmented nematic liquid crystal (NLC) in a honeycomb array is proposed. Surface segregation and liquid crystal self-assembly processes cover curved honeycomb walls of polystyrene (PS) with a high-density polymer brush of an azobenzene side chain liquid crystalline polymer (SCLCP), producing honeycomb polymer films with isolated cavities. Spherical confinement of the cavities with the SCLC brush provides a bipolar nematic director (planar anchoring), whereas UV light irradiation induces a radial configuration (homeotropic anchoring) of NLC droplets. Photoisomerization of azobenzene UV and visible light irradiation repeatedly induces a photoswitchable change between the bipolar and radial modes.

DOI： 10.1002/admi.202100891

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Publishing type：Research paper (scientific journal)   Publisher：The Electrochemical Society of Japan  

DOI： 10.5796/electrochemistry.21-00042

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Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society ({ACS})  

DOI： 10.1021/acs.macromol.0c00838

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Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan (IEE Japan)  

DOI： 10.1541/ieejeiss.140.1182

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Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society ({ACS})  

DOI： 10.1021/acsmacrolett.0c00479

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1038/S41598-020-69605-8

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Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society ({ACS})  

DOI： 10.1021/acsapm.0c00253

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Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society ({ACS})  

DOI： 10.1021/acs.macromol.9b02649

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.7567/1347-4065/AB51A8

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Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry ({RSC})  

DOI： 10.1039/C9SM01731C

PubMed

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Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acs.macromol.9b01817

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

DOI： 10.7567/1347-4065/ab5177

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Other Link： http://iopscience.iop.org/article/10.7567/1347-4065/ab5177/pdf

Language：English   Publishing type：Research paper (scientific journal)  

Copyright © 2019 American Chemical Society. Crystallization that proceeds above the glass transition temperature upon heating the glassy or amorphous state is referred to as "cold crystallization", which has often been observed in supercooled phases of molecular materials followed by the transition to the thermodynamically stable crystalline phase. Although this behavior is common for the macromolecules with high structural flexibility among segments preserving the wide temperature range of corresponding glassy phases, cold crystallization of small molecules is relatively rare and there is still less knowledge on the design guideline of such molecules. Here we report a ferrocene-hinged molecule DC12 carrying two units of didodecyl-substituted pentathiophenes at the 1,1′-positions. Due to the rotational freedom of the ferrocene unit, DC12 forms amorphous solid on cooling from its isotropic melt. The amorphous state was realized even by slow cooling such as 0.1 °C min-1. The possible reason for the easy formation of the amorphous phase is the coexistence of various conformations of DC12 originating from the open conformers of the ferrocene. On heating from the amorphous phase, DC12 shows cold crystallization with the estimated activation energy of 61 kJ mol-1. The crystalline phase is composed of the closed form of DC12 molecules packed in a lamellar fashion, and the degree of crystallinity is remarkably high compared with the case of macromolecular materials. The crystallization is triggered by the intermolecular interactions among the dodecyl chains and rotational flexibility of the ferrocene unit. This work provides an unprecedented example that ferrocenes act as heat-controllable rotational hinges in condensed phases. Considering that the cold crystallization phenomenon is related to heat-storage materials, the design strategy presented in this work will be novel to realize both easily formed amorphous phases and highly crystalline phases formed through cold crystallization.

DOI： 10.1021/acs.jpcb.9b06880

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

New pi-extended dithiarubicene derivatives with multiply cyano-substituted ethenyl groups at the molecular termini (BisDCNE and BisTCNE) and with a dicyanomethylene-substituted quinoidal structure (TCNQE) were synthesized for application in n-type organic semiconductors. In their absorption spectra, it was observed that their pi-conjugations are effectively extended in agreement with the quantum chemical calculation. Thanks to the existence of strong electron-withdrawing groups, BisTCNE and TCNQE exhibited low-lying LUMO energy levels at around -4.2 eV that allow easy electron injection and stable electron transfer under ambient conditions. BisTCNE exhibited the most excellent solubility probably due to the slightly twisted conformation. BisTCNE-based bottom-gate bottom-contact OFET devices exhibited the highest electron mobility (mu(e)) up to 5.5 x 10(-2) cm(2) V-1 s(-1) with an on-off current ratio (I-on/I-off) more than 10(5) under vacuum, and can be operated under ambient conditions without the detrimental decrease of electron mobility (mu(e) = 3.3 x 10(-2) cm(2) V-1 s(-1)). From GIXRD measurements, BisTCNE and TCNQE were found to show an edge-on molecular orientation on the HMDS-treated SiO2 substrate. It is a remarkable result that devices based on BisTCNE exhibited a much better performance compared to devices fabricated from TCNQE with a quinoidal structure often applied to superior n-type OFETs.

DOI： 10.1039/c9tc04325j

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1080/15421406.2019.1648041

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Negatively charged pi-electronic systems prepared by the complexation of anion-responsive dipyrrolyldiketone BF2 complexes with an azobenzene bearing an alkanoate and an aliphatic chain provided unique dimension-controlled assemblies, such as a photo-responsive supramolecular gel.

DOI： 10.1039/c9cc05632g

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society ({ACS})  

DOI： 10.1021/acs.langmuir.9b01689

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1002/CPTC.201800234

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1080/15421406.2019.1648044

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.7567/1882-0786/AB15BB

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society ({ACS})  

DOI： 10.1021/acs.langmuir.8b01824

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/J.ELECTACTA.2019.01.118

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1038/S41598-019-38709-1

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1246/CL.180879

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry ({RSC})  

<p>Highly oriented lamellar films of poly(<italic>N</italic>-dodecylacrylamide) with high molecular weights were formed by nanosegregation between alkyl side chains and a water-adsorbed main chain.</p>

DOI： 10.1039/C8PY01660G

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1038/s41428-018-0100-4

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.orgel.2018.08.019

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Language：Japanese  

J-GLOBAL

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1002/chem.201801399

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1021/acsami.8b05907

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Language：Japanese  

CiNii Article

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society  

Fast proton conduction was achieved in organized lamellar structures with in-plane oriented structure parallel to the substrate surface using a lyotropic liquid-crystalline (LC) property. Alkyl sulfonated polyimides (ASPIs) with bent main chain structure were newly synthesized to investigate relations between the higher order structure and proton transport properties. Proton conductivity of all polyimide thin films was greater than 10-2 S/cm. Grazing-incidence small-angle X-ray scattering (GI-SAXS) revealed that both planar and bent ASPI thin films exhibited humidity-induced lyotropic lamellar structure. Infrared p-polarized multiple-angle incidence resolution (pMAIR) studies revealed that main chain backbones of both planar and bent ASPI thin films show an in-plane orientation parallel to the substrate surface. Results demonstrate that sulfonated alkyl side chains contribute strongly to the lyotropic LC property, which enhances molecular orderings and proton conductivity by water uptake. This study extends knowledge of the molecular design for highly proton conductive polymers with humidity-induced lyotropic LC property.

DOI： 10.1021/acs.macromol.8b00301

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

A negatively charged pi-electronic system was prepared by the complexation of a dipyrrolyldiketone BF2 complex as an anion receptor with a trialkyl-substituted azobenzene carboxylate. The bulk-state properties and photo-responsive behaviors of the azobenzene carboxylate in the ion-pairing form were controlled by complexation with the receptor molecule. The formation of receptor-carboxylate complexes was found to modulate the sizes, shapes, and electronic states of the anionic pi-electronic systems, exhibiting the potential to form a variety of ion-pairing assemblies.

DOI： 10.1246/cl.171128

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Taylor and Francis Inc.  

In general, photoreorientive azobenzene (Az) mesogens in side chain liquid crystalline polymers (SCLCPs) adopt a homeotropic orientation in a thin film state, which can be a drawback for the azimuthal photoalignment. We report herein a SCLCP that shows a planar orientation of Az mesogen achieved by random copolymerization with a planarly orienting cyanobiphenyl (CB) mesogen. Using this planarly orienting SCLCP film, a homogeneous in-plane orientation can be readily achieved by irradiation with linearly polarized light, and further a metastable homeotropic orientation is attained by normal irradiation by non-polarized light. Thus, 3D mesogen alignment controls are achievable on demand. We propose here the utility of the random copolymerization strategy to extend the possibility of photoalignment procedures.

DOI： 10.1080/15421406.2018.1468136

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry  

We developed a surfactant-directed dynamic hybrid film system containing a cationic hygroscopic polysiloxane whose mesostructure is rapidly altered between lamellar and hexagonal phases by the change in surrounding humidity. Immobilization of one phase is successfully achieved by UV-curing through a photoinitiated thiol-ene reaction. This strategy enables the instant activation of a curable LLC mesostructure on-demand by humidification from a dormant state in a dry atmosphere.

DOI： 10.1039/c7cc09226a

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1038/s41428-018-0111-1

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Catechol moieties, which are found in mussel-adhesive proteins, allow the interaction of various kinds of materials that results in substantial adhesion to a wide variety of materials and in the reduction of metal ions to solid metals. Various types of catechol-containing polymers mimicking adhesion and reduction properties have been reported, however, due to its reactivity to a wide variety of functional groups, only a few reports about the formation of block and sequence controlled copolymers containing catechol groups. This is the first report about the synthesis of triblock copolymers containing catechol groups by reversible-addition fragmentation transfer (RAFT) polymerization. The synthesized triblock copolymer forms a core-shell cylinder (CSC) phase-separated structure, in which PVCa domains located the surface of cylinders, and it works as a template for silver nanoparticle arrays and a proton conductive channel. Since triblock copolymer has broader latitude to form phase-separated structures, the triblock copolymer containing catechol groups can be suitable for templates of inorganic nanoparticle arrays.

DOI： 10.1039/c8ra00630j

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Language：English   Publishing type：Research paper (scientific journal)  

This journal is © The Royal Society of Chemistry and the Chinese Chemical Society 2018 Tuning the electrical conductivity of conjugated macromolecules by nanostructure ordering plays a key role in developing carrier transporting materials applicable to flexible organic electronic devices. Alternating copolymers of perylene-3,4,9,10-tetracarboxylic acid diimide (PDI) and flexible macromonomers, poly(dimethylsiloxane) (PDMS), poly(ethylene glycol) (PEG), or poly(propylene glycol) (PPG), were synthesized via simple polycondensation reactions between 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) and bis-amine-terminated corresponding macromonomers. Dynamic traces of absorption and fluorescence spectra of the series of alternating copolymers, with the indication of PDI chromophores, suggested the more foldable nature in tetrahydrofuran of the PDMS-based polymer than of the PEG- and PPG-based polymers. The folding capability of these polymers in solution was confirmed by fluorescence spectra and the absolute fluorescence quantum efficiency values. In the solid films, the condensed state of the polymers showed X-ray diffraction patterns of periodic structures, which depend on the type of macromolecular chains: PEG showed a highly crystallized state in contrast to the slightly crystalline PDI molecules in the PDMS and PPG-based polymers. Photoconductivity upon ultraviolet excitation has been screened by noncontact microwave measurements, and the mobility of electrons has also been characterized based on the kinetic traces of radical anions on the PDI chromophores. The negligible optical absorption observed from the PDMS-based polymers revealed the lowest photocarrier generation yield among the prepared polymers. The observed low conductivity for the PDMS-based, most foldable polymers possibly results from a lower photo-charge generation yield and thermal fluctuations of the flexible PDMS chains. The PEG-based polymer marked the largest electron mobility of 0.2 cm 2 V 1 s 1 , reflecting the highly crystalline nature of the PEG chains.

DOI： 10.1039/c7qm00616k

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The effect of the content of acid groups on the proton conductivity at the interlayer of polymer-nanosheet assemblies was investigated. For that purpose, amphiphilic poly(N-dodecylacrylamide-co-acrylic acid) copolymers [p-(DDA/AA)] with varying contents of AA were synthesized by free radical polymerization. Surface pressure (70 area (A) isotherms of these copolymers indicated that stable polymer monolayers are formed at the air/water interface for AA mole fraction (n) &lt;= 0.49. In all cases, a uniform dispersion of the AA groups in the polymer monolayer was observed. Subsequently, polymer monolayers were transferred onto solid substrates using the Langmuir-Blodgett (LB) technique. X-ray diffraction (XRD) analyses of the multilayer films showed strong Bragg diffraction peaks, suggesting a highly uniform lamellar structure for the multilayer films. The proton conductivity of the multilayer films parallel to the direction of the layer planes were measured by impedance spectroscopy, which revealed that the conductivity increased with increasing values of n. Activation energies for proton conduction of similar to 0.3 and 0.42 eV were observed for n &gt;= 0.32 and n = 0.07, respectively. Interestingly, the proton conductivity of a multilayer film with n = 0.19 did not follow the Arrhenius equation. These results were interpreted in terms of the average distance between the AA groups (l(AA)), and it was concluded that, for n &gt;= 0.32, an advanced 2D hydrogen bonding network was formed, while for n = 0.07, 1 is too long to form such hydrogen bonding networks. The I-AA for n = 0.19 is intermediate to these extremes, resulting in the formation of hydrogen bonding networks at low temperatures, and disruption of these networks at high temperatures due to thermally induced motion. These results indicate that a high proton conductivity with low activation energy can be achieved, even under weakly acidic conditions, by arranging the acid groups at an optimal distance.

DOI： 10.1021/acs.langmuir.7b03160

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

We report a fabrication of a phototunable color filter by combining the Christiansen filter effect and photoisomerization of stilbene. It is known that stilbene isomerizes by irradiation with light, but in that case the light absorption capacity changes only in the ultraviolet region. However, the change in the refractive index due to the isomerization is reflected in the visible light region. A system in which glass beads were dispersed in a solution containing dissolved stilbene as a photochromic dye exhibited a vivid color due to the Christiansen filter effect, in spite of the lack of pigment color. Additionally, we found that the hue of the system can be changed by the isomerization of stilbene upon irradiation with ultraviolet light.

DOI： 10.1246/cl.170603

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

The microphase separation and photoalignment behavior of a diblock copolymer consisting of two kinds of side chain liquid crystalline (LC) polymers are investigated. Here, the mesogens of photoresponsive azobenzene and non-photoresponsive cyanobiphenyl are introduced in the side chains. The azobenzene and cyanobiphenyl mesogens orient homeotropically and planarly, respectively, in a thin film state. The combination of these contrasting orienting properties leads to a formation of vertically oriented lamella in the microphase separation structure. Irradiation with linearly polarized light onto this polymer film induces a highly oriented microphase separation structure having regularly elongated stripe morphology with 30 nm periodicity. The nearly defect-free morphology of this LC-LC diblock copolymer after the photoalignment is a distinct feature when compared with those of coil (amorphous)-LC diblock copolymer films possessing the same azobenzene side chain.

DOI： 10.1002/marc.201600659

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Poly(vinyl alcohol) hydrogels (PVA-Hs) are promising materials for various biomedical applications and have been studied extensively. Low-temperature crystallization is the most popular method used to prepare PVA-Hs with excellent mechanical properties. However, this method uses dimethylsulfoxide (DMSO) as a solvent, which is toxic and difficult to handle. In this study, a novel hot-pressing method was developed for preparing transparent PVA-Hs in order to eliminate the need of DMSO for solubilizing PVA during gelation. Unlike the conventional methods, this method used high initial concentrations of PVA, which made the molding of the gels easy and enhanced their gelation. The hydrogels prepared by hot-pressing showed rapid gelation of the PVA molecules along with an enhanced crystallinity, unlike the hydrogels prepared by freezing and thawing. The efficiency of different solvents (water and DMSO/water mixtures) for the preparation of PVA-Hs by the hot-pressing method was tested. The total amount of crystallites was the same for all the gels irrespective of the solvent used. However, the gels solubilized in only water showed a decrease in the net crystal size. This method not only eliminates the use of DMSO in preparing PVA-Hs but also produces gels with high mechanical properties for future use.

DOI： 10.1038/pj.2017.18

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

This report delineates the design and synthesis of negatively charged azobenzene derivatives that form photo-responsive ion-pairing assemblies. The azobenzene carboxylates possessing aliphatic chains were prepared as photo-responsive anions that promote the formation of ion-pairing dimension-controlled assemblies, including mesophases, when used in conjunction with a tetrabutylammonium (TBA) cation. The photo-responsive properties of the ion pairs and the precursory carboxylic acids in the bulk state were examined by polarized optical microscopy (POM) and X-ray diffraction (XRD), demonstrating that liquid crystal (LC)-liquid and crystal-liquid phase transitions occurred, depending on the number and lengths of the aliphatic chains of each assembly. An ion pair exhibited photo-induced crystal-crystal phase transitions upon switching between two irradiation wavelengths (365/436 nm).

DOI： 10.1002/chem.201701925

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Language：English   Publishing type：Part of collection (book)   Publisher：Springer Japan  

The photoalignment processes in liquid crystal films are based on the occurrence of angular selective photoreactions by linearly polarized light or oblique incidence of light. Alignment of nematic liquid crystals by a surface photoreactive layer has recently become of industrial importance in the fabrication of liquid crystal display panels due to the advantages of non-contact and fine resolution processing. Efforts in this field have also been extending to develop other types of procedures with various liquid crystalline materials. This chapter introduces some new trends in the photoalignment studies including systems of (i) lyotropic chromonic and organic-inorganic hybrids, (ii) block copolymer systems, and (iii) new methods utilizing the free (air) surface for inducing the alignment. These new strategies are expected to provide new directions of materials chemistry and phototechnologies.

DOI： 10.1007/978-4-431-56544-4_21

Scopus

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

The photoinduced surface relief formation via mass transfer upon irradiation with patterned light has long been a subject of extensive investigation. In azobenzene-containing liquid crystalline materials, UV light irradiation that generates the cis isomer leads to the liquid crystal to isotropic photochemical transition. Due to this phase change, efficiency of the mass transfer to generate a surface relief grating (SRG) becomes markedly greater. We have previously indicated that azobenzene-colored SRG-inscribed film can be bleached by removing a hydrogen-bonded azobenzene mesogen. However, this process largely reduces the height feature of the SRG corrugation. Herein, we propose an extended procedure where a colorless mesogen is filled successively after the removal of the azobenzene side chain. The process involves four stages: (i) SRG inscription in a hydrogen-bonded supramolecular azobenzene material; (ii) crosslinking (insolubilization) of the SRG film; (iii) removal of azobenzene mesogen by rinsing with a solvent, and (iv) stuffing the hollow film with a different mesogen. Although the final stuffing stage was insufficient at the present stage, this work demonstrates the possibility and validity of the strategy of mesogen replacement.

DOI： 10.3390/cryst7020052

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

Surface wrinkle formation is ubiquitous in nature, and has become of great importance from the technological viewpoints of surface patterning and fabrications. To date, most of studies on the surface wrinkle formation have been achieved with surface thin films of fixed physical properties formed by deposition or lamination on elastomeric sheets such as poly(dimethyl siloxane) films. This article introduces our recent results on tunable surface wrinkle formation in response to light using azobenzene-containing liquid crystalline polymers. Two strategies are proposed: i) anisotropic wrinkle formation using a photoalignable radical initiator in UV-curable liquid crystal films, and ii) modulations of wrinkle formation using a series of azobenzene liquid crystalline polymers.

DOI： 10.1080/15421406.2016.1277329

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

This report describes the preparation of ultrathin films possessing unusual fingerprint-like morphologies for poly(vinyl catechol-block-styrene) (PVCa-b-PSt) at the air-water interface by simply mixing a solution into water followed by solvent evaporation. Structural analysis and comparison with typical surface micelles of amphiphilic diblock copolymers indicated that precipitation and micelle aggregation played a significant role in the formation and unusual microphase separation of PVCa-b-PSt ultrathin films. In addition, the interior structures of the ultrathin films could be adjusted by adding homo-polystyrene (hPSt). Silver nanoparticle arrays were formed by immersing ultrathin films in aqueous AgNO3 and a microphaseseparated structure in the ultrathin films could act as a template for the arrays.

DOI： 10.1039/c7ra06574d

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

In this paper, we report that poly(N-dodecylacrylamide) (pDDA) formed a well-ordered lamellar structure by annealing in humid conditions. Differential scanning calorimetry measurements of pDDA showed that the crystallized part of the dodecyl side chain in nanodomains melted at -28.5 degrees C and a glass transition temperature of 73.6 degrees C, indicating that pDDA is an amorphous polymer at room temperature (20 degrees C). Thin films of pDDA were prepared by spin coating. Two-dimensional grazing-angle incidence X-ray diffraction (GI-XRD) measurements indicated that the film is composed of randomly oriented lamellar domains. When the film was annealed under 98% relative humidity at 60 degrees C for 24 h, the GI-XRD imaging plate showed spot-like diffraction in the out-of-plane direction with second-order and third-order peaks, indicating that the lamellar plane is oriented parallel to the substrate plane. The lamellar spacing was determined to be 3.25 nm from the Bragg peak. Fourier transform infrared measurements of lamellar structured films showed that the dodecyl side chains are aligned perpendicular to the lamellar plane.

DOI： 10.1039/c6ra27994e

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：SOC POLYMER SCIENCE JAPAN  

High density liquid crystalline (LC) polymer brushes with side chain LC azobenzene were synthesized via surface-initiated atom transfer radical polymerization. LC phase transition behavior was investigated by in situ UV-visible absorption spectroscopy and grazing incidence small angle X-ray scattering (GI-SAXS). The free LC polymer chains in a spincast film exhibited three distinct thermal transitions, glass phase-smectic C (SmC)-smectic A (S(m)A)-isotropic, which correspond to the phase change behavior in the bulk state. On the other hand, the brush film only exhibited the S(m)A phase in the LC temperature range and the S(m)A-SmC phase transition was inhibited. This fact indicates that the LC phase transition behavior in the LC polymer brush is different from that in the free LC polymer of the spincast film. The high density grafted polymer brush structure constrains the mobility of the main chains, which impedes the tilt of mesogenic side chains.

DOI： 10.1295/koron.2016-0045

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

The photoaglinment technologies of liquid crystalline (LC) materials are becoming more important in industries for the fabrication of LC display panels. The photoalignment is based on the anisotropic photoreaction taking place on the substrate surface. We recently proposed a new strategy of surface alignment of LC polymer films utilizing the free (air side) surface instead of solid substrate surface. This short review describes our recent advances of such approach using azobenzene- and cyanobiphenyl- containing side chain liquid crystalline polymers, focusing on the important role of the free surface to control the side chain mesogen orientation. Three series of results are introduced here: i) the first motivation to demonstrate the effect of free surface layer, ii) the alternation of orientation by the rigidity of main chain structure, which is governed by the free surface, and iii) the out-of-plane photocontrol of mesogens by the photoresponsive skin layer at the free surface.

DOI： 10.1080/15421406.2017.1351288

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC ANALYTICAL CHEMISTRY  

Two sulfonated polyimide (SPI) thin films were prepared with water and THF/water mixed solvents, respectively. The SPI thin film prepared with THF/water showed more than 5 times higher proton conductivity than that prepared with water mixed solvent at low relative humidity (RH) and 298 K. In this study, polarized optical microscopy (POM), grazing incidence small angle X-ray scattering (GISAXS), and p-polarized multiple angle incidence resolution spectrometry (pMAIRS) were carried out to investigate liquid crystalline (LC) optical ordered structure, organized structure, and molecular orientation. The molecular ordered parts using LC properties in the SPI thin films exhibited an almost identical structure under the low RH condition. On the other hand, the molecular orientation of the imide C=O groups in the non-ordered parts, which could not be detected by POM and GISAXS, showed different angles. The proton conductivity under low RH conditions is affected by the degree of the molecular orientation in the non-ordered parts of the SPI thin films.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Chemical surface modification of aluminum oxide (AO) nanoparticles with graft copolymer of AO and poly (isobutyl vinyl ether) (PIBVE) (AO-graft-PIBVE) was carried out by ball milling of AO nanoparticles with IBVE in vacuum at low temperature. The AO-graft-PIBVE was evidenced by FT-IR and 1H NMR spectra. The surface modified AO nanoparticles with mono-dispersed particle diameter exhibited structural blue color which was evidenced by photograph, optical spectroscopy (UV-Vis-NIR) and SEM image. The key atoms for the mechanochemical reactions were assigned by the net charge and the distribution of the HOMO and/or LUMO at each atom estimated by molecular orbital calculations. The reaction scheme is proposed; naked Al cations of AO (AO-Al+) were produced by ionic scission of aluminum-oxygen bond by ball milling and trapped at the surface of AO nanoparticles. The AO-Al+ reacted with IBVE, formed a novel bond between the Al-atom of AO-AP and the C-atom of IBVE, and resulted in AO-Al-IBVE+. The AO-AI-IBVE+ sequentially reacted to the C-atom of IBVE, and finally resulted in AO-graft-PIBVE. The PIBVE homopolymer was simultaneously produced by the ball milling of AO with IBVE in vacuum at low temperature. The key atoms for the reactions were assigned by the molecular orbital calculations. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

DOI： 10.1016/j.apt.2016.09.031

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Language：Japanese  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC ANALYTICAL CHEMISTRY  

Immobilization of functional peptides on polymer material is necessary to produce cell-selective scaffolds. However, the expected effects of peptide immobilization differ considerably according to the properties of selected polymers. To understand such combinational effects of peptides and polymers, varieties of scaffolds including a combination of six types of poly(epsilon-caprolactone-co-D,L-lactide) and four types of cell-selective adhesion peptides were fabricated and compared. On each scaffold, the scaffold properties (i.e. mechanical) and their biological functions (i.e. fibroblast-/endothelial cell-/smooth muscle cell-selective adhesion) were measured and compared. The results showed that the cell adhesion performances of the peptides were considerably enhanced or inhibited by the combination of peptide and polymer properties. In the present study, we illustrated the combinational property effects of peptides and polymers using multi-parametric analyses. We provided an example of determining the best scaffold performance for tissue-engineered medical devices based on quantitative data-driven analyses.

DOI： 10.2116/analsci.32.1195

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1002/ange.201607786

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

High-density polymer brushes on substrates exhibit unique properties and functions stemming from the extended conformations due to the surface constraint. To date, such chain organizations have been mostly attained by synthetic strategies of surface-initiated living polymerization. We show herein a new method to prepare a high-density polymer brush architecture using surface segregation and self-assembly of diblock copolymers containing a side-chain liquid-crystalline polymer (SCLCP). The surface segregation is attained from a film of an amorphous base polymer (polystyrene, PS) containing a minor amount of a SCLCP-PS diblock copolymer upon annealing above the glass-transition temperature. The polystyrene portion of the diblock copolymer can work as a laterally mobile anchor for the favorable self-assembly on the polystyrene base film.

DOI： 10.1002/anie.201607786

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Size-controlled metal nanoparticles (NPs) were spontaneously formed when the amphiphilic diblock copolymers consisting of poly(vinyl catechol) and polystyrene (PVCa-b-PSt) were used as reductants and templates for NPs. In the present study, the proton conductivity of well-aligned lamellae structured PVCa-b-PSt films with Ag NPs was evaluated. We found that the proton conductivity of PVCa-b-PSt film was increased 10-fold by the addition of Ag NPs into the proton conduction channels filled with catechol moieties. In addition, the effect of humidity and the origin of proton conductivity enhancement was investigated.

DOI： 10.1021/acs.langmuir.6b02521

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The growth of metal organic coordination network thin films on surfaces has been pursued extensively and intensively to manipulate the molecular arrangement. For this study, the oriented multilayer thin films based on porphyrinic nanoarchitecture were synthesized toward metal-organic coordination networks using surface-induced assembly (SIA). Nanoscale molecular thin films were prepared at room temperature using cobalt(II) ion and porphyrin building blocks as precursors. Stepwise growth with a highly uniform layer was characterized using UV-vis, AFM, IR, and XPS studies. The grazing incidence small-angle X-ray scattering and X-ray reflectivity results remarkably suggested a periodic structure in in-plane direction with constant and high mass density (ca. 1.5 g/cm(3)) throughout the multilayer formation. We propose that orientation of the porphyrin macrocycle plane with a hexagonal packed model by single anchoring mode was tilted approximately 60 with respect to the surface substrate. It is noteworthy that the well-organized structure of porphyrin-based macrocyclic framework on the amine-terminated surface substrate can be achieved efficiently using a simple SIA approach under mild synthetic conditions. The synthesized thin film provides a different structure from that obtained using bulk synthesis. This result suggests that the SIA technique can control not only the film thickness but also the structural arrangement on the surface. This report of our research provides insight into the ordered porphyrin-based metal-organic coordination network thin films, which opens up opportunities for exploration of-unique thin film materials for diverse applications.

DOI： 10.1021/acs.langmuir.6b01251

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The preparation of urea (bonded) cross-linked multilayer thin films by sequential deposition of bifunctional and tetrafunctional molecular building blocks is demonstrated. Multilayer growth as a. function of deposition cycles was inspected using UV-Vis absorption spectroscopy.. From infrared results, three characteristic infrared bands of amide I, amide II, and asymmetric v(a)(N-C-N) strtching confirmed the formation of polyurea networks by alternate dipping into solutions of amine and isocyanate functionality monomers. The deconvoluted component of the C is and N is spectra obtained by X-ray photoelectron spctroscopy shows clear evidence of stable polyurea networks. The enhancement of structural periodicity with film growth was demonstrated by grazing incidence small-angle X-ray scattering measurements. The thin film near the substrate surface seems to have an amorphous structure. However, molecular ordering improves in the surface normal direction of the substrate with a certain number of deposited layers. Constant mass density was not observed with deposition cycles. The mass density increased up to 16% within deposited layers from proximate layers to those extending away from the substrate surface. This difference in the packing density might derive from the different degrees of cross-linking among layers proximate to the substrate surface and extending away from the substrate surface.

DOI： 10.1021/acs.langmuir.6b00540

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The orientation behavior of mesogens in a polyacrylate with cyanobiphenyl (CB) side chain in thin films was investigated in detail by UV-vis absorption spectroscopy and grazing incidence small-angle X-ray scattering (GI-SAXS) measurements using both high-energy X-rays of Cu K alpha line (lambda = 0.154 rim) and low-energy synchrotron X-rays (lambda = 0.539 nm). By changing the film thickness ranging 7-200 nm, it is concluded that the planar orientation is predominant for thin films with thickness below 10-15 nm. This planar mesogen orientation near the substrate surface coexists with the homeotropically aligned CB mesogens in films thicker than 30 nm. For the thinnest 7 nm film, the planar orientation is unexpectedly lost, which is in consort with a disordering of medic layer structure. Peculiar orienting characteristics of CB mesogen are suggested, which probably stem from the tendency to form an antiparallel arrangement of mesogens due to the strong dipole moment of the terminal cyano group.

DOI： 10.1021/acs.langmuir.6b00538

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

Block copolymer phase separation has been employed to form templates for the fabrication of nanoscale patterns of metals due to their characteristic size scales that range from several nanometers to tens of nanometers. In the present work, poly(vinyl catechol-block-styrene) PVCa-b-PSt synthesized with various compositions forms unique microphase-separated structures. Silver nanoparticles are spontaneously formed inside of the PVCa phases due to the reductive properties of the catechol moieties. The alignment and formation of silver nanoparticle arrays is successfully achieved without the need for high-temperature thermal treatment or chemical reduction processes. The present system can be applied to the formation of nanoparticle arrays with a wide variety of metals by control of their arrangement.

DOI： 10.1002/macp.201500504

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

For efficient photoresponses of liquid-crystal (LC) azobenzene (Az) polymer systems, planar LC orientation of the Az mesogenic group is required because the light irradiation process usually occurs with normal incidence to the film surface. However, LC molecules with a rodlike shape tend to orient perpendicularly to the film surface according to the excluded volume effect theory. This review introduces new approaches for inducing planar orientation in side-chain LC Az polymer films via interface and surface molecular designs. The planar orientation offers efficient in-plane photoalignment and photoswitching to hierarchical LC architectures from molecular LC mesogens and LC phases to mesoscopic microphase-separated structures. These approaches are expected to provide new concepts and possibilities in new LC polymer devices.

DOI： 10.1002/tcr.201500232

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Language：Japanese  

J-GLOBAL

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：HINDAWI LTD  

Although surface immobilization of medical devices with bioactive molecules is one of the most widely used strategies to improve biocompatibility, the physicochemical properties of the biomaterials significantly impact the activity of the immobilized molecules. Herein we investigate the combinational effects of cell-selective biomolecules and the hydrophobicity/ hydrophilicity of the polymeric substrate on selective adhesion of endothelial cells (ECs), fibroblasts (FBs), and smooth muscle cells (SMCs). To control the polymeric substrate, biomolecules are immobilized on thermoresponsive poly(N-isopropylacrylamide-co-2-carboxyisopropylacrylamide) (poly(NIPAAm-co-CIPAAm))-grafted glass surfaces. By switching the molecular conformation of the biomolecule-immobilized polymers, the cell-selective adhesion performances are evaluated. In case of RGDS (Arg-Gly-AspSer) peptide-immobilized surfaces, all cell types adhere well regardless of the surface hydrophobicity. On the other hand, a tri-Arg-immobilized surface exhibits FB-selectivity when the surface is hydrophilic. Additionally, a tri-Ile-immobilized surface exhibits EC-selective cell adhesion when the surface is hydrophobic. We believe that the proposed concept, which is used to investigate the biomolecule-immobilized surface combination, is important to produce new biomaterials, which are highly demanded for medical implants and tissue engineering.

DOI： 10.1155/2016/2090985

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Fused pi-conjugated imidazolium compounds bearing two or three long alkoxy chains and various counter anions were systematically prepared following our reported synthetic route. On the basis of DSC measurements and POM observations, the combination of three alkoxy chains longer than the dodecyl group and moderately coordinating anions was important to obtain an enantiotropic mesophase. VT-XRD measurements coupled with a single crystal X-ray structure of a model compound revealed a hexagonal columnar structure supported by ionic interactions. The regularity of the self-organized nanostructure was governed by the alkoxy chain length and the coordinating ability of the counter anion. In the solution state, UV-vis and fluorescence peak maxima were influenced by the number of alkoxy chains and independent of the chain length and anion character. On the contrary, the alkoxy chain length and the coordinating ability of the counter anion had a large impact on the fluorescence spectra in the solid state. A longer wavelength emission at around 560 nm was observed for compounds with the highly regular hexagonal columnar structure. From the result of fluorescence lifetime measurements, the interaction between fused pi-conjugated imidazolium cations was suggested.

DOI： 10.1039/c5ra25496e

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

To date, reversible alignment controls of liquid crystalline materials have widely been achieved by photoreactive layers on solid substrates. In contrast, this work demonstrates the reversible out-of-plane photocontrols of liquid crystalline polymer films by using a photoresponsive skin layer existing at the free surface. A polymethacrylate containing a cyanobiphenyl side-chain mesogen adopts the planar orientation. Upon blending a small amount of azobenzene-containing side-chain polymer followed by successive annealing, segregation of the azobenzene polymer at the free surface occurs and induces a planar to homeotropic orientation transition of cyanobiphenyl mesogens underneath. By irradiation with UV light, the mesogen orientation turns into the planar orientation. The orientation reverts to the homeotropic state upon visible light irradiation or thermally, and such cyclic processes can be repeated many times. On the basis of this principle, erasable optical patterning is performed by irradiating UV light through a photomask.

DOI： 10.1021/acs.langmuir.5b04325

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Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publisher：日本化学会コロイドおよび界面化学部会  

CiNii Article

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER PHYSICAL SOC  

Electronic transport was investigated in poly(3-hexylthiophene-2,5-diyl) monolayers. At low temperatures, nonlinear behavior was observed in the current-voltage characteristics, and a nonzero threshold voltage appeared that increased with decreasing temperature. The current-voltage characteristics could be best fitted using a power law. These results suggest that the nonlinear conductivity can be explained using a Coulomb blockade (CB) mechanism. A model is proposed in which an isotropic extended charge state exists, as predicted by quantum calculations, and percolative charge transport occurs within an array of small conductive islands. Using quantitatively evaluated capacitance values for the islands, this model was found to be capable of explaining the observed experimental data. It is, therefore, suggested that percolative charge transport based on the CB effect is a significant factor giving rise to nonlinear conductivity in organic materials.

DOI： 10.1103/PhysRevLett.115.196801

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

In side-chain-type liquid-crystalline (LC) polymers, the main chain rigidity significantly affects the LC structure and properties. We show herein a relevant new effect regarding the orientation of side-chain mesogenic groups of LC polymers in a thin-film state. A subtle change in the main chain structure, i.e., polyacrylate and polymethacrylate, leads to a clear alternation of mesogens in the homeotropic and planar modes, respectively. This orientational discrimination is triggered from the free surface region (film air interface) as revealed by surface micropatterning via inkjet printing.

DOI： 10.1021/acs.langmuir.5b02442

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Laminated bilayer films comprised of photoresponsive azobenzene-containing liquid crystalline polymer skin layers adhered on a thick elastomeric substrate were prepared, and the wrinkle formation upon uniaxial compression was investigated. Irradiation with UV light at 365 nm led to the disappearance of the wrinkle or reduction of wrinkle wavelength, depending on the content of azobenzene unit in the polymer. Such photoresponsive modulations of wrinkle formation could be well correlated with the photoinduced changes in the Young's modulus determined by indentation-retraction force curve measurements using an AFM cantilever. Additionally, the thickness modulation of the skin layer caused by the photoinduced mass migration can also be applied to modify the wrinkle wavelength. These photoresponsive surface wrinkle modulations are anticipated to offer new possibilities for the surface microfabrication technology.

DOI： 10.1021/acs.macromol.5b01577

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The effect of molecular ordering and ordered domain size on molecular weight dependent proton conductivity in well-organized sulfonated polyimide (SPI) thin films has been investigated using both low molecular weight (LMw, M-w = 1.3 x 10(4)) and high molecular weight samples (HMw, M-w, = 2.6 x 10(5)). Analyses of the films by grazing incidence small-angle X-ray scattering (GISAXS) revealed that the HMw, SPI film exhibits the higher degree of inherent liquid crystalline-like lamellar ordering, and that it is consistent with a preferential in-plane main chain packing. Such molecular ordering and the in-plane oriented structure can have considerable influence on the proton transport characteristics in thin films. The larger ordered domains in the HMw SPI thin film with a thickness of approximately 500 nm shows the significant proton conductivity enhancement to a value of 2.6 x 10(-1) S/cm (at 25 degrees C and 95% relative humidity), which is more than an order of magnitude higher value than that of the smaller ordered domains in the LMw SPI thin film with less molecular ordering. The larger ordered domains in the HMw, SPI thin film influence the conducting characteristics attributable to the fewer liquid crystalline-like domain boundaries relative to LMw, SPI films because the smaller ordered domains in the LMw, SPI thin film more obviously exhibit large-scaled domain boundaries, which can disrupt the fast ion transportation.

DOI： 10.1021/acs.jpcc.5b03292

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Language：English   Publisher：MARY ANN LIEBERT, INC  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

DOI： 10.1080/15421406.2015.1075356

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

Investigations on the photoaglinment processes of liquid crystalline materials started around 25years ago, and currently great developments have been made in both academic and industrial areas. However, there remain many issues to be explored in this field. This short review introduces our recent advances regarding the photoalignment and realignment process using azobenzene-containing liquid crystalline polymer materials. Two topics are involved here: the photoalignment of microphase separation structures of block copolymer films, and photoalignment controls from the free surface of a liquid crystalline polymer film.

DOI： 10.1080/15421406.2015.1050284

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

High proton conductivity Was achieved in a polymer multilayer film with a well-defined two dimensional lamella structure The multilayer film was prepared by deposition of poly(N-dodecylacryamide-co- acrylic acid) (p(DDA/AA)) monolayers onto a solid substrate using the Langmuir-Blodgett technique. Grazing-angle incidence X-ray diffraction measurement of a 30 layer film Of,p(DDA/AA) showed strong diffraction peaks in the-out-of-plane direction at 2 theta = 2.26 degrees and 4.50 degrees revealing that the multilayer film had a highly uniform layered structure with a monolayer thickness of 2.0 nm. Tho proton conductivity Of the p(DDA/AA) multilayer film. parallel to the layer plane direction was 0.051 S/cm at 60 degrees C and 98% relative-humidity with a low activation energy of 0.35 eV, which is comparable to perfluorosulfonic acid membranes. The high conductivity and low activation energy resulted from the formation of uniform two-dimensional proton-conductive nanochannels in:the hydrophilic regions of the multilayer film. The proton conductivity of the multilayer film perpendicular to the layer plane was determined to be 2.1 X 10(-13) S/cm. Therefore, the multilayer film showed large anisotropic conductivity with an anisotropic ratio of 2.4 x 10(11).

DOI： 10.1021/acs.langmuir.5b00036

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The realignment process of azobenzene-containing liquid crystalline (LC) block copolymer films by irradiation with linearly polarized light (LPL) was investigated in detail by time-resolved grazing incidence X-ray scattering measurements using a synchrotron beam. By using a newly synthesized diblock copolymer possessing a poly(hexyl methacrylate (PHMA) block with a lowered glass transition temperature (T-g = -5 degrees C), intense X-ray scattering signals were obtained, which favorably provided precise and detailed time course profiles and information on the interplay between the hierarchical structures involved along the realignment process. The LC layers were softened and fluctuated at an early stage by LPL irradiation which induced shrinkage of the cylinder to cylinder distance of microphase separation patterns before the alignment change. Interestingly, the ordering process of the MPS cylinder array of larger hierarchical structure proceeded faster than that of the azobenzene LC layer of smaller feature size in the realigned state. Decisive evidence was obtained to support the subdomain rotation mechanism in the realignment process.

DOI： 10.1021/acs.macromol.5b00299

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A rod-shaped azobenzene derivative possessing a 2-benzoyl-2-propanol moiety (Az-PIni) was synthesized. This molecule was highly compatible with calamitic nematic liquid crystal (LC) systems and showed dual photofunctions as a photocommander for the alignment of LCs upon linearly polarized light (LPL) irradiation and a photoinitiator for the radical polymerization in these media. The dual photofunctions were achieved simultaneously by irradiation with 365 nm LPL, or stepwisely with 436 nm LPL for the photoalignment, and successively with 254 nm light for the photoinitiated polymerization. In a nematic LC cell, these combined processes provided a persistent uniform alignment. When a polymerizable LC monomer film was coated on an elastomeric sheet, the anisotropic photopolymerization of the photoaligned monomer initiated by Az-PIni led to a uniformly aligned wrinkle formation via polymerization shrinkage.

DOI： 10.1021/ma5025279

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Language：Japanese   Publishing type：Research paper (scientific journal)  

CiNii Article

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

A series of block copolymers composed of an amorphous poly(butyl methacrylate) (PBMA) block connected with an azobenzene (Az)-containing liquid crystalline (PAz) block were synthesized by changing the chain length and polymer architecture. With these block copolymer films, the dynamic realignment process of microphase separated (MPS) cylinder arrays of PBMA in the PAz matrix induced by irradiation with linearly polarized light was studied by UV-visible absorption spectroscopy, and time-resolved grazing incidence small angle X-ray scattering (GI-SAXS) measurements using a synchrotron beam. Unexpectedly, the change in the chain length hardly affected the realignment rate. In contrast, the architecture of the AB-type diblock or the ABA-type triblock essentially altered the realignment feature. The strongly cooperative motion with an induction period before realignment was characteristic only for the diblock copolymer series, and the LPL-induced alignment change immediately started for triblock copolymers and the PAz homopolymer. Additionally, a marked acceleration in the photoinduced dynamic motions was unveiled in comparison with a thermal randomization process.

DOI： 10.1039/c5sm01140j

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELECTROCHEMICAL SOC JAPAN  

The organized structure and proton transport property in sulfonated polyimide (SPI) thin film have been studied, much less is known at the interfacial charge transport during confinement of such materials. The proton conductivity of SPI thin film is correlated well with the highly oriented polymer structures as determined by infrared (IR) p-polarized multiple-angle incidence resolution spectrometry (p-MAIRS) and in situ RH dependent synchrotron grazing incidence X-ray diffraction (GI-XRD). The high proton conductivity of 2.8 x 10(-1)S cm(-1) at 80 degrees C and 90% RH was achieved in the highly oriented SPI thin film. In contrast, the bulk SPI showed the drop of conductivity value at high relative humidity region, which is due to the significant structural disorder accompanied by the strong interaction between the sulfonic acid side chains and water molecules. (C) The Electrochemical Society of Japan, All rights reserved.

DOI： 10.5796/electrochemistry.82.865

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The pathways toward linearly polarized light (LPL)-induced alignment switching in a diblock copolymer film composed of liquid crystalline (LC) azobenzene (Az) and amorphous poly(butyl methacrylate) (PBMA) blocks were studied in detail using polarized UVvis absorption spectroscopy, grazing incidence small-angle X-ray scattering measurements, and polarized optical microscopy and transmission electron microscopy observations. The hierarchical structures of microphase-separated cylinders of PBMA in a smectic LC Az layer matrix were prealigned by LPL and then irradiated by orthogonal LPL, which resulted in alignment switching to the orthogonal direction. In this process, the large prealigned domains were divided into substantially smaller domains at the submicrometer level, and then the structures were realigned in the orthogonal direction in a strongly cooperative manner, most likely through the domain rotation mechanism. The alignment change consisted of three stages: (i) fluctuations in the smectic layer of LC Az side chains in the initial state and breaking up of smaller grains to the submicrometer level before the orientation change (induction period), (ii) actual rotation of the divided domains driven by the photoinduced reorientation of Az mesogens (action period), and (iii) slower fusion and growth of smaller domains in the orthogonally realigned direction (postgrowth period). New aspects of dynamic self-assembly behavior in which different hierarchical structures are involved are proposed.

DOI： 10.1021/ma501803g

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

We reported the long-range perpendicular and horizontal orientation of polystyrene cylinders in polystyrene-b-poly(methyl acrylate) (PS-b-PMA) films with thickness scale from hundreds micrometers to millimeters. Dissolving block copolymer (BCP) in selective solvents forms PS micelles in solution, which could be trapped in films after ordinary solvent casting. Controllable alignment of perpendicular and horizontal cylinders from the directional coalescences of PS spheres along permeation directions of annealing solvent into the film was achieved, i.e., solvent permeating from surface of film led to perpendicular PS cylinders while from edge resulted in horizontal cylinders. Polarizing optical micrographs and mu-beam SAXS confirmed the directional coalescences mechanism during the orientation process and that the cylindrical structure was achieved throughout a macroscopic scale. Solvent components influenced the orientation behavior, and the mixed solvents containing 2540% (volume fraction) methanol were favorable to form highly oriented cylinders.

DOI： 10.1021/ma501033a

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

We recently demonstrated that addition of a surface active polymer (SAP) that segregates on the free (air) surface in liquid crystalline (LC) block copolymer films crucially alters the orientation of the mesogens and microphase separation domains. A block copolymer of poly(butyl methacrylate) (PBMA) combined with an azobenzene LC polymer has been blended as SAP in a polystyrene-based LC block copolymer films possessing similar structure. The present work reveals that the polymer design, the blend ratio, and molecular weight of the surface active polymer significantly affect the orientational alternation for the block copolymer film. The orientational alternation effect by the free surface segregation becomes significantly efficient when SAPs with higher molecular weight is employed.

DOI： 10.1080/15421406.2014.940487

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

A facile and innovative method for the fabrication of highly fluorescent micro-patterns is presented, which operates on the principle of phototriggered phase transition and physical mass migration in the crystalline film of a cyanostilbene-type aggregation-induced enhanced emission (AIEE) molecule ((Z)-2,3-bis(3,4,5-tris( dodecyloxy) phenyl) acrylonitrile) with liquid-crystalline (LC) mesomorphic behavior.

DOI： 10.1002/adma.201304250

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Polystyrene-b-poly(methyl acrylate) (PS-b-PMA) block copolymer with PS volume fraction of 25.2 vol% was synthesized by atom transfer radical polymerization. Non-pretreated silicon wafers were used as the substrates to prepare perpendicular oriented PS cylinders in PMA matrix via solvent annealing which could induce the transformation of spheres to vertically oriented and hexagonally packed cylinders. The spherical microdomains were formed after the evaporation of solvents from the solutions of the block copolymer in selective solvents mixed from methanol, acetone and dichloromethane. The thickness of films could be as thick as 1000 nm, which were much thicker than usual cases and the cylinders came from the directional coalescence of the spheres, thus any pre-treatments of the substrates were not required for perpendicular orientation. The structures were characterized by small angle X-ray scattering (SAXS), transmission electron microscope (TEM), atom force microscopy (AFM) and grazing incidence small angle X-ray scattering (GISAXS). (c) 2014 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymer.2014.01.060

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

The orientation of liquid crystal molecules is very sensitive towards contacting surfaces, and this phenomenon is critical during the fabrication of liquid crystal display panels, as well as optical and memory devices. To date, research has focused on designing and modifying solid surfaces. Here we report an approach to control the orientation of liquid crystals from the free (air) surface side: a skin layer at the free surface was prepared using a non-photoresponsive liquid crystalline polymer film by surface segregation or inkjet printing an azobenzene-containing liquid crystalline block copolymer. Both planar-planar and homoeotropic-planar mode patterns were readily generated. This strategy is applicable to various substrate systems, including inorganic substrates and flexible polymer films. These versatile processes require no modification of the substrate surface and are therefore expected to provide new opportunities for the fabrication of optical and mechanical devices based on liquid crystal alignment.

DOI： 10.1038/ncomms4320

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Studies of proton transport in confined thin polymer electrolytes are essential for providing additional information regarding the structure-property relationships of such materials. Using a combination of proton transport measurements and structural characterization, we explored the effect of proton conductivity in sulfonated polyimide (SPI) under both bulk and nanostructured thin film systems. A SPI film confined to a thickness of approximately 530 nm shows significant proton conductivity enhancement to a value of 2.6 x 10(-1) S cm(-1) (95% RH at 298 K), which is almost one order of magnitude more proton conductive than the bulk system (3.0 x 10(-2) S cm(-1) at 90% RH and 298 K). In thin films, the preferred chain packing along the in-plane direction can have considerable influence on the charge transport characteristics, which leads to the enhanced proton conductivity. Infrared (IR) p-polarized multiple-angle incidence resolution spectrometry (p-MAIRS) and in situ grazing-incidence small-angle X-ray scattering (GISAXS) were used to investigate the direction of polymer orientation and the changes in the internal polymeric structure under various humidity conditions, respectively. Under high-humidity conditions, the strong interaction between the side-chain sulfonic acid groups and water molecules causes an abrupt change in the internal structure in bulk SPI. Such a structural rearrangement results in a liquid-crystal-like ordered polymer structure. The RH dependent FTIR-ATR studies reveal that the accumulation of a large fraction of water molecules with stronger hydrogen bonding at high humidity regions causes the huge deviation in the internal morphology of the bulk samples.

DOI： 10.1039/c4ta00579a

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DOI： 10.1107/S2053273314098441

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：SOC POLYMER SCIENCE JAPAN  

The orientation of cylindrical and lamellar micro-phase separated structures of some block copolymers (BCP) in thin films was investigated by grazing incident small-angle X-ray scattering and atomic force microscopy. The thin films were made from solution using selective solvents for the major component of the BCP. The spherical structure was arrested initially in the film with a thickness of 500 nm(-1) mu m. Solvent annealing, using common solvents, induced a morphology transition from spherical to a vertically oriented cylindrical (lamellar) structure. A neutral solvent for both components in the BCP was found to be effective for the perpendicular orientation of the micro-domains. (C) 2014, The Society of Polymer Science, Japan

DOI： 10.1295/koron.71.104

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Higher order derivative spectra were applied to UV-VIS spectral changes of a liquid-crystalline polymer with azobenzene side chains exposed to linearly polarised 436 nm light at an elevated temperature to reveal the participation of non-aggregated as well as two types of aggregated species in in-plane as well as out-of-plane photoreorientation individually.

DOI： 10.1039/c4ra10151k

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Charge transport anisotropy in pi-stacked poly(3-hexylthiophene-2,5-diyl) (P3HT) monolayers was investigated. The monolayers were prepared using a Langmuir-Blodgett technique and were uniaxial but homogeneous two-dimensional sheets. Nanoscale electrical measurements were carried out using metal electrodes with a submicrometre gap between them in order to exclude breaches that occasionally occur along the chains. A remarkable degree of isotropy in both the conductivity and mobility was found. The conductivity isotropy implies that charge transport is dominated by fatal defects in polymers arising at structural and electrical discontinuities, even in the absence of large morphological defects. It was found that the mobility along the pi-stacking direction can exceed that along the polymer chain in monolayers with good crystallinity. This high mobility along the pi-stacking direction is thought to be an inherent charge transport characteristic that has so far been obscured in solid state conjugated polymers with complex microstructures.

DOI： 10.1088/0022-3727/46/42/425303

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Alignment methods of nematic liquid crystals (LCs) by surface photoreactions on substrate surfaces were initially proposed around 1990, and the photoalignment technology of nematic LCs has recently been integrated into the LC device fabrication industry due to its profitable features. Accumulated efforts in this field have revealed that applications of photoalignment processes are not limited to conventional nematic LCs but that a variety of functional materials can also be manipulated according to this principle. Target materials have now been extended to thermotropic smectic LCs, discotic LCs, LC polymers, block copolymers, gel networks, conjugated polymers, and organic semiconductors and lyotropic systems including chromonic LCs and inorganic organic mesostructured hybrids. Through these photochemical approaches, many types of photopatterning for both topographical and orientational modulations have become feasible. This article reviews photoalignment processes applied to a wide range of materials, surveying relatively recent work. Some important related alignment and patterning processes are also introduced to clarify the significance of these photoalignment techniques. (C) 2013 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymer.2013.08.058

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Vertically oriented cylinders via the directional coalescence of the spheres embedded in the blend thin films from polystyrene-b-poly(4-hydroxyl styrene) (PS-b-PHS) and PEG induced by solvent annealing were achieved. Removal of PEG water led to the formation of nanochannels throughout the films. The diameter of these channels could be as small as 9 nm which might enhance the applicability of the nano-porous films as size-selective membranes and controllable drug delivery systems for the objects less than 10 nm. © 2013 The Royal Society of Chemistry.

DOI： 10.1039/c3nr01491f

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PubMed

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

High-density polynorbornene azobenzene liquid-crystalline brushes are synthesized on quartz substrates by surface-initiated ring-opening metathesis polymerization (SI-ROMP) using Grubbs third-generation catalyst. The grafting process is controlled over the thickness of the brush from a solid-supported substrate in a stoichiometric manner. A highly ordered liquid-crystal arrangement was formed for such brushes as revealed by spectroscopic measurements and grazing angle X-ray diffraction analysis. Marked features of this method in the structure and photoalignment behavior are unveiled by comparison with brushes made by surface-initiated atom-transfer radical polymerization (SI-ATRP).

DOI： 10.1021/la4002847

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Language：Japanese  

CiNii Article

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Language：English   Publishing type：Research paper (scientific journal)  

Photoinduced in-plane motions are explored for a series of surface-grafted diblock copolymers comprising of an amorphous chain block and a liquid crystalline (LC) azobenzene (Az) side chain polymer block. In this architecture, amorphous polymers with different glass transition temperature (Tg) and the LC Az polymer are stepwisely grafted on substrate surfaces by the surface initiated atom transfer radical polymerization. Amorphous polymers employed are poly(hexyl methacrylate) (PHMA), poly(butyl methacrylate) (PBMA), and poly(methyl methacrylate) (PMMA) with Tg of -20, +27, and +110 C, respectively. The extent of photoinduced in-plane anisotropy of the LC Az layer by linearly polarized light irradiation at optimal temperatures are in the order of PHMA &gt
PBMA &gt
PMMA which coincides with that of lowering T g. Thus, the photoinduced motions of the LC Az blocks are coupled with the dynamic nature of the underlying amorphous chain anchored to the substrate. The structural information obtained by the grazing incidence angle X-ray diffraction measurements further shows the important role of the amorphous polymer layer in the ordering and photoalignment of LC mesogens on the top. © 2013 American Chemical Society.

DOI： 10.1021/ma401536r

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1246/bcsj.20130172

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

A liquid crystalline (LC) azobenzene homopolymer brush film of poly[4-(10-methacryloxydecyloxy)-4-pentylazobenzene] (P5Az10MA), and two diblock copolymer brushes consisting of the same LC azobenzene (Az) block connected with poly(hexyl methacrylate) block (PHMA-b-P5Az10MA) have been synthesized on initiator-immobilized quartz surfaces by atom transfer radical polymerization. In the diblock polymer brushes, the length of PHMA blocks tethering to the substrate surface were changed (26nm and 51nm). The orientation and structural features of the liquid crystalline block, containing an Az mesogenic group of the polymer brushes were evaluated by UV-vis spectroscopy and grazing incident X-ray diffraction measurements. Upon irradiation with 436nm linearly polarized light (LPL), the levels of photoinduced in-plane anisotropy and reorienting behavior among the brushes showed significant differences as a result of degree of freedom of the flexible buffer chain spacers.

DOI： 10.1080/15421406.2013.843766

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

DOI： 10.1002/anie.201300560

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Poly(hexyl methacrylate)-block-poly[4-(10-methacryloxydecyloxy)-4'-pentylazobenzene] (PHMA-b-P5Az10MA) diblock copolymer brush was stepwisely synthesized on an initiator-immobilized quartz surface by atom transfer radical polymerization. In this chain design, a flexible PHMA chain was connected between a liquid crystalline (LC) azobenzene (Az) block and a solid substrate. The orientation and structural features of the smectic layer spacing of the azobenzene (Az) block at the outer surface were essentially the same as those of P5Az10MA homopolymer brush. Upon irradiation of 436 nm linearly polarized light (LPL) at a temperature of liquid crystalline (LC) state of the Az polymer, the block copolymer brush exhibited a significant improvement in the induction of in-plane optical anisotropy compared to a corresponding homopolymer brush as revealed by UV-vis spectroscopy and grazing angle incidence X-ray diffraction measurements. The temperature dependence of the optical and structural anisotropy and photoreorientation behavior unveiled a significant lubricant role of the flexible chain block for the improvement of photoresponsive motions. This work proposes an idea to decouple the photoinduced motions of the upper photoresponsive block from the restriction by the substrate through introduction of a "buffer spacer" chain.

DOI： 10.1021/ma300843x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A dendritic molecule of poly(propylene imine) whose periphery is modified with photoresponsive mesogenic azobenzene units was synthesized. This compound exhibited highly ordered smectic B or smectic A layer structure orienting parallel to the substrate in the film state. When this film of 90 nm thickness on a hydrophilic substrate was exposed to UV (365 nm) light, the initial flat film morphology started to form holes followed by a drastic transformation to form separated dome structure of micrometer levels. Upon continuous UV light irradiation, the domain height increased and reached to a level of ca. 8-fold higher than that of the initial thickness, which can be correlated with the disordering of layer structures as revealed by grazing angle incidence X-ray diffraction measurements. This phototriggered dewetting behavior depended on the film thickness. The thinner film resulted in local migrations to form the smaller and more homogeneous domes. The dewetting was observed below a threshold thickness of 100 nm. By UV light irradiation through a photomask, phototriggered migration at micrometer distances also occurred. By the combination of phototriggered migration and concerted dewetting, characteristic hierarchical morphologies were formed, depending on the initial film thickness. This work proposes a new possibility to control and design the dewetting processes of thin films using the dendritic material.

DOI： 10.1021/ma301170x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

A polyimide film containing a cholesteryl moiety spin-coated on a solid substrate is treated with vacuum ultraviolet light from a Xe-2(*) excimer lamp at 20 Pa. This procedure generates oxidized chemically functional groups, such as hydroxyl groups, selectively on the top-most surface without changing the nature of the bulk polymer. Onto the chemically functionalized surface, photofunctional units such as azobenzene and cinnamate units are attached at a monolayer or sub-monolayer level. When nematic liquid crystal (LC) cells are fabricated, such photoresponsive surfaces work as effective 'command surfaces' for photoswitching the zenithal LC orientation and photoaligment layers to achieve the homogeneous azimuthal orientation applicable for vertical alignment mode LC devices. The proposed photochemical treatment provides a simple but versatile alternative process for the preparation of surface molecular films comparable to self-assembled monolayers or Langmuir-Blodgett films. Polymer Journal (2012) 44, 639-645; doi:10.1038/pj.2012.45; published online 28 March 2012

DOI： 10.1038/pj.2012.45

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPLIED PHYSICS  

We report charge transport anisotropy of ultrathin-film transistors of poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) with controlled in-plane chain orientation prepared by a modified Langmuir-Blodgett method. The field-effect mobility of a five-monolayer transistor reached 3.0 x 10(-4) cm(2) V-1 s(-1) with a large anisotropy ratio of about 7.5 between parallel and perpendicular chain orientations. This is in sharp contrast to a nearly two-dimensional mobility anisotropy of the previously reported ultrathin poly(3-hexylthiophene) transistors having a pi-overlapped lamellar structure. The quasi-one-dimensional anisotropy of the present device is ascribed to a weak pi-pi stacking structure due to a flat-on-like orientation of MEH-PPV confirmed by atomic force microscopy. (C) 2012 The Japan Society of Applied Physics

DOI： 10.1143/APEX.5.021602

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Language：English   Publishing type：Research paper (scientific journal)  

Nematic liquid crystalline (LC) cross-linked polymer gel sheets containing 3 mol % azobenzene (Az) unit were prepared and swollen by a nematic solvent of 4′-pentyl-4-cyanobiphenyl (5CB). This 5CB-swollen gel sheet exhibited a discontinuous volume change around the nematic-isotoropic phase transition temperature of the LC gel (T NI G). UV irradiation at a temperature slightly lower than T NI G provoked a large volume transition (expansion) due to a loss of nematic order within the gel sheet caused by the trans-to-cis photoisomerization of Az. The volume was reverted by irradiation with 436 nm light. By templating the colloidal crystal film of monodispersed silica particles, a LC gel sheet possessing a microporous structure was also prepared. Due to the facilitated diffusion of 5CB, the microporous LC gel exhibited significant enhancements in the extent and rate of the photoinduced volume transition. © 2012 American Chemical Society.

DOI： 10.1021/mz300447j

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

DOI： 10.1002/anie.201201346

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

We report in this paper photoinduced-dewetting phenomena observed for thin films (thickness &lt; 100 nm) of a series of dendritic liquid crystalline materials with different spacer length (carbon number changing from n = 6 to 12) at their azobenzene units in the periphery. Spincast films of these dendrimers were prepared and exposed to UV light (365 nm) at various photon doses at room temperature. Atomic force microscopic observations of the dewetting forming process were performed step by step with increasing the UV illumination time for the dendrimer with the shortest spacer (n = 6). We observed how the dewetting bumps appeared from an initially flat spincast film and finally reached ca. eightfold of the initial film thickness. The dendrimer with n = 8 exhibited dewetting but the mass migration distance was significantly limited than that of n = 6. Dendrimers with longer spacer lengths (n = 10 and 12) did not exhibit dewetting behavior in the same conditions. These differences were discussed in terms of thermophysical properties of the materials.

DOI： 10.1080/15421406.2012.689144

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

The Suzuki (for O1-O3) and Stille (for O4) coupling polymerization of 2-(phenylazo)imidazole bearing the benzyl protecting group at the 1-position gave conjugated oligomers. The transformation from the neutral imidazole in the conjugated oligomer O2, consisted of the alternating 2,5-didecyl-1,4-phenylene unit, to the cationic imidazolium salt O2S was performed. Depending on the chemical structure of coupling partners, the absorption maximum of conjugated oligomers showed red shift or blue shift from that of the model compound M with the benzene ring at the 4,5-positions. The absorption maximum wavelength of the cationic conjugated oligomer O2S showed a blue shift from that of the neutral conjugated oligomer O2. The trans-to-cis photoisomerization of the azoimidazole unit in conjugated oligomers was observed by irradiating the light at 436 nm, and the conversion degree to the cis structure had a rough correlation with the maximum absorption wavelength of materials. The trans-to-cis photoisomerization in the film state was sluggish. On the other hand, the cis-to-trans thermal isomerization of the azoimidazole unit was confirmed and the absorbance returned to the initial state before the photoisomerization. The trans-to-cis photoisomerization of the cationic conjugated oligomer O2S required large energy, and the prolonged light irradiation might decompose the azoimidazole unit. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 4993-5000, 2011

DOI： 10.1002/pola.24958

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CiNii Article

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER SCIENTIFIC PUBLISHERS  

A mixed film of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) with 6-(4-[(4-hexylphenyl)azo]phenoxy}hexanoic acid (6Az5COOH) were prepared on water by co-spreading method. The resulting films were transferred onto mica at various surface pressures. Atomic force microscopy (AFM) and pi-A isotherm measurements revealed that both PS and p4VP blocks in PS-b-P4VP forms spread monolayer on water with the assist of 6Az5COOH at low surface pressures. Upon compression on water, we observed that the P4VP/6Az5COOH parts in the hybrid film are collapsed selectively at an early stage and form dot array morphology. In addition, gold cluster dots were deposited selectively on the dots in the dot array film by metallization based on deposition of HAuCl4 to the P4VP chain and reduction with dimethylamino borane. These results strongly support the fact that the "inversed" surface micelles are formed on water via hybridization of PS-b-P4VP with 6Az5COOH.

DOI： 10.1166/jnn.2011.3896

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

The dry beads milling of a mixture of 9,10-dipropoxyanthracene (DPA) as an electron donor and surface-modified silica nanoparticles was conducted in the absence or in the presence of a photoacid generator (PAG) as an electron acceptor to give powdery nanocomposites. Fluorescence measurements indicated no mechanochemical change in the crystal structure of DPA after the nanohybridisation. The co-milling with PAG resulted in solid-state fluorescence quenching, whereas quenching efficiency was considerably dependent on the nature of PAG. The solid-state sensitised photoacid generation through the electron transfer was demonstrated by the solid-state photocolouration of leuco-dye of crystal violet lactone.

DOI： 10.1039/c0cp00034e

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

Photoreorientation of a stripe pattern consisting of an MPS structure in a Langmuir-Blodgett monolayer by irradiation with linearly polarized light is achieved for the first time using a PDMS/poly(methacrylate) diblock copolymer with a liquid crystalline azobenzene-containing side chain. The stripe MPS pattern in the trans azobenzene state is diminished by photoisomerization to the cis form upon UV light irradiation. By the erasure of the MPS structure, the anisotropic photo-oriented stripe pattern is generated upon irradiation with linearly polarized visible light, the orientation of the stripe pattern being orthogonal to the electric vector of the light.

DOI： 10.1002/macp.201000474

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The development of vertically aligned mesochannels in organic/inorganic hybrid films is in high demand and a challenging issue. However, there are no clear guiding principles to attain the surface-mediated vertical alignment. This work proposes the first clear versatile strategy to achieve the vertical alignment by utilizing the pi-pi interaction between the organic template molecule of a planar discotic liquid crystalline and 2D a-plane of graphite. The crucial role of the pi-pi interaction can be verified by the exploration with other substrates such as silicon wafer surfaces with varied surface energy (water contact angle: 5 degrees-105 degrees), quartz plates, and polymer films, which provided common parallel alignment with respect to the substrate plane.

DOI： 10.1021/ja106220J

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A family of homopolymers and random copolymers consisting of an azobenzene (Az)-containing methacrylate and hexyl acrylate were synthesized varying the copolymerization ratio. With increasing the content of hexyl acrylate, the temperature range of the liquid crystalline (LC) state was monotonously lowered. These polymer films were subjected to an exposure to the patterned irradiation to evaluate the mass transport behavior. This approach revealed that the efficient mass migration is strongly coupled with the thermal properties. Under the optimized conditions, two types of irradiation procedures were adopted: (i) two-step irradiation involving the UV (365 nm) light illumination and subsequent patterned visible light (488 nm of argon ion laser or 436 nm Hg line) and (ii) one-step patterned irradiation with UV light. After the irradiation with a photomak, the former method caused the mass transfer from the illuminated regions to shaded ones, whereas the latter led to the migration in the inversed direction. In both procedures, the migration consistently proceeded at the boundaries from the smectic A phase regions to the isotropic ones in the photochemically generated phase patterns. More general guidelines are proposed to exert the efficient mass transport in the LC Az polymers by adjusting the polymer design and temperature.

DOI： 10.1021/ma100328e

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

Ultrathin-film polymeric transistors with controlled in-plane chain orientation have been fabricated based on Langmuir-Blodgett technique by cospreading liquid crystal molecule with regioregular poly(3-hexylthiophene). The mobilities parallel to the chain direction reached 0.001-0.01 cm(2)/V s for 1 to 5 monolayer thick transistors. Mobility ratio was about 2 for the parallel and perpendicular directions. Electron spin resonance (ESR) signals of the field-induced polarons exhibited clear in-plane anisotropies due to unpaired pi-electrons. The anisotropic ESR spectra together with the optical dichroism determine the detailed molecular orientations in the channel of such ultrathin transistors.

DOI： 10.1063/1.3421538

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

A generic way to prepare nano-sized molecular crystals in large scale is described. The dry mechanical grinding of a mixture of molecular crystals with surface-modified Stober silica nanoparticles gave voluminous hybridised powders with core-shell nanostructures, which were revealed by TEM and EFTEM measurements. Fluorescence spectra of the hybrids of emissive crystals suggested that crystal structures of the bulk are preserved even after the milling. Calorimetric measurements disclosed that melting points of crystals are lowered as a result of the nanohybridisation and that the depression of melting point and heat of fusion are reversibly proportional to shell thickness.

DOI： 10.1039/b925120k

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Language：English   Publishing type：Research paper (international conference proceedings)  

A new method of measuring specular X-ray reflectivity curves with a time resolution of milliseconds to seconds is developed. A horizontally convergent X-ray beam having a one-to-one correlation between its direction and energy is realized by a curved crystal or a laterally graded multilayer on an elliptic substrate. The X-ray beam is then incident on the surface of the specimen placed at the focus in such a way that the glancing angle in the vertical direction is the same for all X-ray components, which are reflected in the vertical direction by the surface and diverge in the horizontal plane. The perpendicular momentum transfer continuously changes as a function of the horizontal ray direction since the wavelength change similarly. The normalized linear intensity distribution across the beam direction measured downstream of the specimen represents the X-ray reflectivity curve. Examples of time-resolved measurements of X-ray reflectivity curves are shown. © 2010 American Institute of Physics.

DOI： 10.1063/1.3463368

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

When an amphiphilic block copolymer is directly spread from an organic solution, the morphology of the surface micelles is not in general controlled because the structure is rapidly frozen after the solvent evaporation. In contrast, we have developed a new versatile method to generate highly regular ordered nanopatterns of the surface micelles on water, which involves the process of two dimensional (2D) hybridization with a polar liquid crystal molecule, 4'-pentyl-4-cyanobiphenyl (5CB) [Langmuir 22 (2006) 5233]. The present work extends this approach using a family of diblock copolymers of polystyrene-block-poly(4-vinylpyridine) changing the chain length of the two polymer blocks. It is found here that the dot-to-dot distance and the dot size can be precisely controlled on-demand by the length of the polymer blocks. Such structural regulations cannot be attained without the 5CB hybridization. Due to the high reproducibility of the morphology formation, this process should be of practical significance to 'engineer' the 2D patterns in the range of some tens of nanometers. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.tsf.2009.07.078

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A new class of organic-inorganic liquid crystalline hybrid materials consisting of an azobenzene derivative and titanium oxide (6Az5COO-TiO and 6AzlCOO-TiO) was synthesized. 6Az5COO-TiO with a C5 spacer showed a smectic liquid crystalline phase. The organic 6Az5COO and TiO inorganic components in the hybrid film were oriented perpendicular and parallel 10 the Substrate plane, respectively, to form a layered structure. The structure of the liquid crystalline hybrid material was formed via nanophase separation of the organic and inorganic components. This film wits then subjected to the inscription of surface relief structure formation by patterned UV irradiation. The efficiency of the phototriggered mass transfer showed a clear temperature dependency. The optimal temperature range was around 130 degrees C, which corresponds to the lower edge of the endothermic peak in the differential scanning calorimetric profile. The mass transfer was initiated at a surprisingly small energy dose of irradiation [40 mJ cm(-2) (8 mW cm(-2) for 5 s)] in this hybrid material, as has been observed for fully organic soft liquid crystalline polymer systems. It is anticipated that this new type of hybrid material have potential for microfabrication of optical and photocatalytic elements.

DOI： 10.1021/cm900970p

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Hydrophobic poly(9,9-di-n-octylfluorene-alt-benzothiadiazole) [F8BT] formed an ideal spread monolayer on a water surface by the cospreading method with liquid crystal molecule, 4'-pentyl-4-cyanobiphenyl [5CB]. The F8BT/5CB hybrid monolayers were characterized by surface pressure-area (pi-A) isotherm measurements and atomic force microscopy (AFM). F8BT does not form a homogeneous monolayer by direct spreading on water from a single solution. The mixed film of two components, F8BT and 5CB, gave a characteristic pressure lift-off attributed to the hybrid monolayer above the 5CB plateau. AFM observation revealed that the spread monolayer of the F8BT formed on the top of the 5CB monolayer on water with the thickness of ca. 1.7 mn. The F8BT/5CB hybrid monolayers could be fully transferred onto a solid substrate, and pure F8BT monolayers were obtained after volatilization of 5CB by gentle hearing. Polarized UV-vis absorption spectra showed that the main chain of F8BT preferentially oriented perpendicular to the compressive direction at the surface pressure of 10 mN m(-1) on water. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.synthmet.2009.01.021

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Language：English   Publishing type：Research paper (scientific journal)  

リビングラジカル重合を利用し、光応答性液晶高分子の高密度ブラシを調製した。その特異な構造を明らかにするともに、組織構造の変化のみにて光応答性が飛躍的に向上する示した。

DOI： 10.1021/ma802010x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

A thin film of a new liquid crystalline azobenzene-titania precursor hybrid shows sensitive phototactic motions to form a relief structure. This topologically patterned film can be directly converted to a micropatterned anatase-type crystalline TiO2 film by photodecomposition and pyrolysis.

DOI： 10.1039/b916494d

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

The photoalignment of liquid crystalline azobenzene-containing polymers has been an active area of research, which intends to apply for optical elements such as rewritable optical memory, photorefractive and photomechanical devices. However, the photoalignment behavior is hardly studied in nano-confined environments. We introduce herein our current activities on the new types of photoalignment controls of azobenzene-containing liquid crystalline polymer materials; (i) polymer chains tethered (grafted) onto a substrate and (ii) nanostructures formed by a block copolymer. New platforms for the photoalignment technologies are anticipated in these photoactive thin film systems.

DOI： 10.1080/15421400903057827

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

A new photoresponsive calamitic liquid crystal molecule possessing (1-cyclohexenyl)phenyldiazene as a close analogue of azobenzene was synthesized and a comparative study with the corresponding azobenzene analogue carried out.

DOI： 10.1039/b906716g

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Highly efficient migration has been observed for soft liquid-crystalline azobenzene-containing polymer films to form surface relief gratings (SRGs). The efficient migration is probably driven by the interfacial instability at boundaries between the smectic liquid-crystalline phase and photoinduced isotropic one. However, this migration system suffers from long-term and heat stability. This work proposes a new post-fixation method by utilizing the [2 + 2] photo-dimerization reaction of a cinnamoyl unit introduced into the polymer. The polymer synthesis, the properties of SRG formation, and drastic improvement of the stability towards heating and solvent exposure are described.

DOI： 10.1039/b900146h

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Publishing type：Research paper (scientific journal)  

Nano-structured MoO3/carbon clusters/ZrO2 composite material has been successfully obtained by the microwave-treatment of a MoCl5/ZrCl4/starch/graphite complex. The compositions of the resulting composite materials were determined using inductively coupled plasma (ICP) spectroscopy, elemental analysis, and surface characterization by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The ultraviolet-visible (UV-vis), X-ray photoelectron spectra (XPS) and electron spin resonance (ESR) spectra of the composites were also measured. ESR spectra of the composite materials suggest that they have visible light-responsive catalytic ability with an electron transfer process of MoO3 → carbon clusters → ZrO2. © 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/J.CAP.2008.05.007

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The spread monolayer formation of hydrophobic poly (3-alkylthiophene)s (P3ATs), regioregular poly(3-hexylthiophene) (HT-P3HT), regioregular poly(3-dodecylthiophene) (HT-P3DT), and regioirregular poly(3-hexylthiophene) (RI-P3HT), were attained on the water surface via cospreading with a liquid-crystal molecule, 4'-pentyl-4-cyanobiphenyl (5CB). The spread monolayers were characterized by R-A isotherms, Brewster angle microscopy (BAM), and atomic force microscopy (AFM). The molecular area for the cospread mixtures of P3ATs and 5CB expanded more than that of pure P3ATs as shown from the pi-A isotherms. BAM revealed that the mixed film forms the monomolecularly uniform and flat films on water. AFM elucidated that the spread monolayer of the hydrophobic P3ATs formed on the top of the 5CB monolayer on water with thicknesses of ca. 1.6 and ca. 2.6 nm for the two P3HTs and HT-P3DT, respectively. The P3AT/5CB hybrid monolayers could be fully transferred onto a solid substrate, and pure P3AT monolayers were obtained after volatilization of 5CB by gentle heating. The multilayer formation of pure MAT monolayers was prepared by layer-by-layer deposition involving repeating horizontal deposition and successive volatilization of 5CB. Grazing angle incidence X-ray diffraction measurements showed that the lamella plane of the P3ATs is perfectly oriented parallel to the substrate plane in the resulting thin films. This shows a marked contrast with those obtained by spin casting using the identical polymer, where both in-plane and out-of-plane lamellae are involved. These thin films with perfectly controlled lamella orientation should be of great significance as the model system for evaluating the charge mobility for organic polymer electric devices.

DOI： 10.1021/la801899f

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Language：English   Publisher：CHEMICAL SOC JAPAN  

Light provides practical and versatile tools for structure formation and its tuning of soft materials. This article briefly over-views recent developments of photoalignment and phototuning of nanostructured materials focusing onto the 2D material systems. Two topics are involved; i) phototuning and alignment of microphase-separated nanostructures in block copolymers containing a photoisomerizable unit and ii) photoalignment of organic/silica nanohybrids prepared on a polymer film with photocrosslinkable unit.

DOI： 10.1246/cl.2008.484

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Here we report on a chromic slide-ring gel consisting of polyrotaxane by using a close-packed colloidal crystal as a template. In the slide-ring gel, the polymer chains with bulky end groups are not covalently cross-linked like chemical gels nor do they interact attractively like physical gets, but are topologically interlocked by figure-of-eight cross-links. The slide-ring gel has freely movable cross-links, which have a pulley effect on tensile deformation. This effect improves the mechanical properties of polymer gels. In this work, this physically and mechanically optimized polymer gel was used to make stimuli-responsive photonic band gap materials. Our gel exhibits solvatochromic behavior based on the change in structural color.

DOI： 10.1021/ma0715627

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

Light irradiation provides significant tools for material structuring and processing. In this article, the photo-orientation processes of the organic/inorganic hybrid materials recently achieved in our laboratory are briefly introduced. Irradiation of linearly polarized light to a polymer film containing a photoisomerizabke azobenzene or photocrosslinkable cinnamoyl unit leads to the induction of anisotropic molecular orientations on the surface. This molecular anisotropic surface structure can be transferred to a controlled orientation of nanostructures of organic/inorganic. hybrid films at macroscopic scales. Two classes of lyotropic/silica systems have been applied to the photo-orientation procedures, i.e., ordinary surfactant systems and chromonic ones. These processes can be regarded as the extended applications of the so-called command surface systems, which photochemically regulate the molecular orientations of liquid crystals. (C) 2008 The Ceramic Society of Japan. All rights reserved.

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Language：English   Publisher：The Ceramic Society of Japan  

Light irradiation provides significant tools for material structuring and processing. In this article, the photo-orientation processes of the organic/inorganic hybrid materials recently achieved in our laboratory are briefly introduced. Irradiation of linearly polarized light to a polymer film containing a photoisomerizabke azobenzene or photocrosslinkable cinnamoyl unit leads to the induction of anisotropic molecular orientations on the surface. This molecular anisotropic surface structure can be transferred to a controlled orientation of nanostructures of organic/inorganic hybrid films at macroscopic scales. Two classes of lyotropic/silica systems have been applied to the photo-orientation procedures, i.e., ordinary surfactant systems and chromonic ones. These processes can be regarded as the extended applications of the so-called command surface systems, which photochemically regulate the molecular orientations of liquid crystals.

DOI： 10.2109/jcersj2.116.361

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Other Link： https://jlc.jst.go.jp/DN/JALC/00310202569?from=CiNii

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

The efficient photo-triggered surface relief formation in the H-boned supramolecular liquid crystalline system was performed for the first time. This supramolecular framework leads to facile and successful detachment of azobenzene unit from the SRG inscribed film with exact retention of the morphological periodicity.

DOI： 10.1002/adma.200701110

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

We recently found that the chromonic mesophase structure of an azo dye can be immobilized by a silica network to form a chromonic-silica nanohybrid. This work reports the first demonstration of the macroscopic photoalignment and photopatterning of this nanohybrid via surface-mediated orientational transfer from a photocrosslinkable liquid crystalline polymer (PPLC). Irradiation with linearly polarized light (LPL) 300 nm above the PPLC film followed by an appropriate annealing process led to strong in-plane molecular orientation in the film. The precursor sol solution containing a chromonic forming azo dye and tetraethoxysilane in the presence of an anionic surfactant and 2-(2-aminoethoxy) ethanol was placed onto this aligned film by the static deposition or dipping method. After drying, the chromonic columns hybridized with silica were macroscopically oriented orthogonal to the LPL direction, namely the orientation of the dye molecule being parallel to it. In the dip coating process, a combination of photoalignment and flow induced orientation allowed clear micropatterning of the column orientations, which could be readily discerned when observed with a polarizing film.

DOI： 10.1039/b802145g

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Some dye molecules self-aggregate to exhibit a lyotropic columnar liquid crystal state (chromonic liquid crystal) via pi stacking in relatively highly concentrated aqueous solutions. In this work, the chromonic liquid crystal structure was immobilized, for the first time, with silica networks by way of the sol-gel condensation process. The immobilization of the columnar structure was successfully attained in the presence of 2-(2-aminoethoxy)ethanol, which favorably mediates the interface between the anionic charge of the dye aggregates and the silica network. Without this molecule, the sol-gel process gave rise to a transformation from columnar to lamellar structure. Both spin-coating and dip-coating methods gave essentially the same results. In the dip-coated films, the dye molecules were aligned over a large area with orientation orthogonal to the lifting direction.

DOI： 10.1021/la701557q

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

Slide-ring topological gels with mobile cross-linking units are a new class of soft materials that exhibit distinct features differing from those of conventional chemically or physically crosslinked gels. Photoresponsive behavior arising from the dynamic nature of the cross-linkers is demonstrated for a slide-ring, gel prepared by adding azobenzene units to the mobile a-cyclodextrin units of a poly(ethylene oxide)based polyrotaxane (see figure).

DOI： 10.1002/adma.200700457

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

We have recently demonstrated a markedly photosensitive surface relief gratings (SRG) formation in thin films of liquid crystalline azobenzene-containing polymers, which proceeds from a cis-rich state of the azobenzene [Zettsu et al. Adv. Mater. 2001, 13, 1693; Macromolecules 2004, 37, 8692]. Such polymers exhibited unexpected enhancements in the sensitivity to light for the completion of SRG formation, the required energy dose being similar to 10(3)-fold lower than that for other azobenzene polymers systems widely employed. Here we report detailed results on the systematic explorations for understanding the migration mechanism. The cis-isomer content at the initial state and irradiation intensity crucially influenced the migration efficiency and the resulting relief structure in nonlinear manners. The Zisman plot showed that the light irradiation leads to a large change in the critical surface tension. Such results strongly suggest that the photochemically induced phase transition and the resulting spatial modulations in the physical properties in the film play the essential roles for the SRG formation. On the basis of this knowledge, the SRG formation via a sensitized excitation was demonstrated for the first time by incorporation of a near-infrared absorbing dye.

DOI： 10.1021/ma0706428

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Liquid crystalline (LC) polymer brushes containing a mesogenic azobenzene (Az) moiety are synthesized on a quartz or silicon substrate by surface-initiated atom transfer radical polymerization. The molecular orientation of the Az units and the LC properties in the grafted chains are evaluated by UV-vis spectroscopy, polarized optical microscopy, and grazing incidence X-ray diffraction measurements. The Az side chains of the grafted chains exhibited a smectic LC phase in which the smectic layers are oriented perpendicular to the substrate with a parallel orientation of the mesogens. In contrast, a spincast film of the identical LC polymer without grafting to the surface shows layer structures parallel to the substrate. A drastic effect of tethering one end to the substrate on the LC orientation is demonstrated.

DOI： 10.1021/la063467h

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

DOI： 10.1021/cm0630845

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A microfabrication technique is presented to fabricate a mesostructured inorganic/organic composite film, i.e., silica/cetyltrimethylammonium chloride (CTAC) film, with near-perfect site-selectivity on a large surface area based on a spatially regulated growth method. To precisely regulate the site-selective growth of this mesocomposite film at the solid/liquid interface, we designed a novel microtemplate consisting of a "dual-component" self-assembled monolayer (SAM) with alternating hydrophobic trifluorocarbon (CF3) and cationic amino (NH2) groups. First, (heptadecafluoro-1,1,2,2-tetrahydrodecyl)trimethoxysilane (FAS)-SAM was formed onto Si substrate covered with native oxide (SiO2/Si) from vapor phase. The substrate was then photolithographically micropatterned using 172 nm vacuum UV light. Finally, the micropatterned FAS-SAM was immersed in a solution of 1 vol % (aminoethylaminomethyl)phenethyltrimethoxysilane (AEAMPS) in absolute toluene. Due to these treatments, a dual-SAM microtemplate with CF3- and NH2-terminated surfaces was fabricated, as evidenced by lateral force microscopy, ellipsometry, and X-ray photoelectron spectroscopy. Using this template, the microfabrication of a mesocomposite film was demonstrated. As a control, the micropatterned hydrophobic FAS-SAM template (composed of CF3- and OH-terminated surfaces) was also treated under the same conditions. Optical microscopy and atomic force microscopy confirmed that the formation of the continuous mesocomposite film proceeded only on the FAS-SAM-covered regions, while the AEAMPS-SAM-covered regions remained free of deposits. This shielding effect also remained constant regardless of the pattern's geometry, i.e., the interval distance between the FAS-SAM-covered areas in the pattern. Through this approach, we were able to obtain well-defined 5-, 10-, and 20-mu m wide mesocomposite microlines over the entire 10 x 10 mm(2) area with high area-selectivity. On the other hand, when the SiO2 regions were not terminated with the cationic NH2 groups, cluster formation proceeded not only on the hydrophobic CF3 regions but also on the SiO2 regions, particularly with an increase in the pattern interval distance, resulting in lower final pattern resolution.

DOI： 10.1021/la0614051

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We report herein the microphase separation structures (nanostructures) observed in Langmuir-Blodgett monolayers of an ABA block copolymer comprising of azobenzene-containing methacrylate and poly(ethylene oxide) as A and B block, respectively. After spreading this polymer on water in the trans and cis form of azobenzene, the monolayer is transferred onto mica at 1 mN m(-1). The morphological features are observed by atomic force microscopy. The features of the nanostructures formed in the monolayers have obviously different features in the isomerization state of azobenzene. The conversions of the morphological features accompanied by the isomerization of azobenzene are attempted by light irradiation and dark adaptation. This paper focuses on the features in morphological conversions attained in the photo- and thermal processes. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.colsurfa.2005.10.081

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

A new photo-aligning technique for mesochannels of a silica thin film transferred from a liquid crystalline photo-crosslinkable polymer (poly[6-(4-(4'-methoxycinnamoyloxy)biphenyloxy)hexylmethacrylate] (PMBCi)) film has been developed in our group. Herein, we also adopt a non-liquid crystalline photo-crosslinkable polymer, poly(vinyl cinnamate) (PVCi), to evaluate the role of liquid crystallinity for inducing the alignment of mesochannels of the silica films. Optical anisotropy of the thin films of the two photo-crosslinkable polymers (PVCi and PMBCi) was induced by irradiation with linearly polarized UV (LPUV) light. The photo-induced anisotropy of both films were sufficient for alignment of nematic liquid crystal molecules, however, mesoporous silica films were aligned only on the liquid crystalline PMBCi film as revealed by in-plane X-ray diffraction (XRD) measurements and optical microscopy. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.colsurfa.2005.10.072

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We report herein characteristic spreading behavior of amphiphilic block copolymer, polystyrene-block-poly(4-vinyl pyridine) (PS-P4VP) at the air-water interface. When the polymer was spread from cyclohexane, a theta solvent for PS and a poor solvent for P4VP, onto the air-water interface, an unexpected sharp temperature dependent change was observed in the surface pressure-area curves. In contrast, when non-theta solvents such as chloroform were used, only negligible temperature dependency was observed. In the cyclohexane solution, the aggregate size of the block copolymer strongly depends on the solution temperatures as revealed by dynamic light scattering measurements. The phenomena observed for cyclohexane should involve the coil-globule conformational transition taking place in the theta solvent. To our knowledge this work presents the first clear example that the aggregation state of polymers in solution is directly reflected to the two-dimensional spreading behavior at the air-water interface. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.colsurfa.2005.10.080

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A highly ordered dot array pattern of surface micelles on water is formed by a spread monolayer of an amphiphilic block copolymer, polystyrene-block-poly(4-vinylpyridine) (PS-4VP), via hybridization with a liquid crystal molecule, 4'-pentyl-4-cyanobiphenyl (5CB), on water. Simple co-spreading of PS-4VP with 5CB provides a flat homogeneous monolayer of PS-4VP on water without the aggregation of PS blocks. With increasing surface pressure, well-defined dots of the PS blocks start to grow and are arrayed in a highly ordered hexagonal structure. The exact coincidence of the surface pressure-area curves for the hybrid monolayer in the compression and expansion processes confirms that the flat spread monolayer and the dot array are formed on water in the equilibrium state by a self-assembly process.

DOI： 10.1021/la060350k

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

Optical 3D alignment of nanocylinders has been successfully attained for thin films of a block copolymer (see figure) comprising azobenzene-containing liquid-crystalline polymers and poly(ethylene oxide) via photoinduced massive migration. ne out-of-plane and inplane alignments are achieved by controlling the film thickness and selection of linear polarization direction upon illumination, respectively.

DOI： 10.1002/adma.200502573

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Two-dimensional-hexagonal mesoporous silica thin films with aligned mesochannels in one direction at large scales will be favorably applied in optics, electronics, separation technologies, and so forth. We propose herein a new photo-aligning and micropatterning technique for mesochannels of a silica thin film using a photo-cross-linkable polymer film with a cinnamoyl group. The polymer film was uniaxially photo-oriented by exposure to the linearly polarized UV (LPUV) light. On this film, the mesoporous silica thin film was synthesized by various preparation methods. The orientation of the mesochannels was evaluated by in-plane X-ray diffraction (XRD) measurements. It was shown that the mesochannels were aligned perpendicular to the polarized direction of the irradiated LPUV light. In-plane XRD measurements and transmission electron microscopic and optical microscopic observations of the silica films revealed that photo-orientation of the mesochannels is controlled over the whole surface area of the film. In addition, micropatterning of the photo-aligned mesoporous silica films was readily attained by exposure to the LPUV light passed through a photomask.

DOI： 10.1021/cm052359y

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Photopolymerization of liquid crystalline monomers was achieved within photoaligned mesoporous silica film. After resolving the template of silica networks, bundles of nanofibers containing polymer chains with a narrow molecular weight distribution were obtained.

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

We have synthesized ABA triblock copolymers consisting of azobenzene polymers as A block and poly(dimethylsiloxane) as B block by atom transfer radical polymerization method. The monolayers of the triblock copolymers were spread on a water surface from a chloroform solution and transferred onto mica. The triblock copolymer monolayer in the trans form exhibited fingerprint patterns. After the UV light was Irradiated to the monolayer film at a highly humidified condition, the patterns about disappeared. Successive irradiation with the linearly polarized visible light brought the anisotropic reorientation of the azobenzene moiety. This led to the formation of the uniaxial stripe patterns in the microphase-separated structure.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

We have newly designed and synthesized a family of copolymers containing a hexyl acrylate and an azobenzene monomer prepared at various mixing ratios. In this series, the phototriggered relief formation of the polymers could be discussed simply on the basis of their thermal properties because complicated factors such as nanophase separation and aggregation of azobenzenes are suppressed for the polymers. When the polymer films were irradiated with UV light through a photomask, the polymers showed migrations from dark regions to bright regions, resulting in a formation of "hill" structures. Such behavior is in contrast to that found in our previous work.

Scopus

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ELSEVIER SCIENCE BV  

We report characteristic spreading behavior of amphiphilic block copolymers, polystyrene-block-poly(4-vinyl pyridine) (PSm-P4VPn) at the air-water interface. When the polymers were spread from cyclohexane, a theta solvent for PS and a poor solvent for P4VP, onto the air-water interface, unexpected sharp temperature dependent changes were observed in the surface pressure-area curves. In the cyclohexane solution, the aggregate sizes of the block copolymers strongly depended on the solution temperature as revealed by transmittance measurements. These phenomena observed for cyclohexane should be attributed to the coil-globule conformational transition taking place in the theta solvent. The phase transition temperature in solution and at the air-water interface linearly enhanced with the increase of the molecular weight of PS segments. To our knowledge this work presents the first clear example that the aggregation state of polymers in solution is directly reflected to the two-dimensional spreading behavior at the air-water interface.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ELSEVIER SCIENCE BV  

Photo-triggered mass migration in thin films of photoresponsive azobenzene (Az)-containing polymers leads to development-free formation of surface relief structure. This work shows that this method can be applied to a thin film of a diblock copolymer consisting of an Az-containing liquid crystalline segment and poly(ethylene oxide). A corrugated surface structure following the interference periodicity was efficiently formed with the assist of 4'-phenyl-4-cyanobiphenyl (5CB). The content of 5CB greatly influenced the migration efficiency which was evaluated by both the first-order diffraction and surface topology measurements.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

DOI： 10.1021/ja051200j

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

A photocrosslinkable polymer liquid crystal (PPLC) can be used to form aligned mesoporous silica thin films. Crosslinking the biphenyl mesogens with linearly polarized UV light results in a photo-oriented film whose orientational order is subsequently increased by annealing. Addition of a precursor sol produces high-quality silica films (see Figure) which can be used for optical devices that incorporate functional dyes or metal clusters into the channels.

DOI： 10.1002/adma.200401418

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

Organized molecular systems provide alluring light-driven actuation systems. They can be migrated or deformed themselves or control states of other ordered materials. This paper presents our two recent topics on light-driven organized monolayers and thin films comprising photochromic azobenzene-containing liquid crystalline polymers; i) photo- alignment of nanochannels in mesoporous silica film, and ii) light-triggered instant mass migration in a thin film state, which can be utilized as a conveyance system for micropatterning of light-inert molecules and materials.

DOI： 10.1080/15421400590946235

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

The hybridization of different types of materials frequently leads to specific performances and structure formation. Our current interest is focused onto dynamic performances photofunctional polymers assisted by hybridized liquid crystal molecules. In this paper, two current topics undergoing in our laboratory are presented. In the former part, monolayer formation of hydrophobic polysilanes assisted by polar calamitic liquid crystal molecules is described, This is the first example of monolayer formation of a fully dydrophobic polymer on water. The latter part shows the marked acceleration of lateral mass migration promoted by photoirradiation in azobenzene-containing polymers. Both systems utilize common and general features of liquid crystals, namely, dynamic properties (fluidity) maintaining orientational order in the molecular assemblies. We show herein the high validity of liquid crystals for thin film processing of polymers.

DOI： 10.1117/12.509180

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

DOI： 10.1021/ja012105n

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The monolayer formation of a hydrophobic polymer, poly(dihexylsilane) (PDHS), on the water surface was performed for the first time through cospreading with a liquid crystal molecule, 4 ' -pentyl-4-cyanobiphenyl (5CB). The spread monolayer formation of PDHS was confirmed by surface pressure-area (pi -A) isotherm measurements, Brewster angle microscopy (BAM), atomic force microscopy (AFM), and W-visible absorption spectroscopy. The cospread film of PDHS and 5CB on water exhibited isotherms giving a new sharp pressure increase attributable to the hybridization of PDHS/5CB. The lift-off area corresponding to this pressure increase was in exact proportion to the mixing ratio (R = [Si unit of PDHS]/[5CB]). BAM revealed a highly homogeneous feature of the hybrid monolayers on water at the lift-off area of the PDHS/5CB hybrid film. The AFM images of these hybrid monolayers transferred onto mica indicated that the thickness of the spread PDHS film on the 5CB monolayer ranges from 1 to 1.5 nm. Most probably, the molecularly spread PDHS backbone is positioned on top of the 5CB monolayer. The hybrid films could be transferred onto a solid substrate. W-visible absorption spectra showed that the Si main chain of PDHS adopts only a helical-gauche (disordered) conformation on both water and a quartz substrate, which shows a sharp contrast with that of the bulk film. On the solid substrate, a preferential orientation of the Si chain was observed in the lifting direction depending on the surface pressure applied for deposition.

DOI： 10.1021/la001469a

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

Mixed films containing poly(dihexylsilane) (PDHS) and liquid crystal (LC) molecule were prepared onto a rubbed poly(vinyl alcohol) film by spin-casting. The conformational state and the alignment of the PDHS backbone were investigated by polarized UV-visible absorption spectroscopy. The absorption band ascribed to the crystalline state of PDHS in the mixed film showed a red shift from that of a pure PDHS film. The PDHS backbone in the mixed film was aligned parallel to the rubbing direction. The magnitude of the red shift and the alignment order of PDHS was enhanced by annealing at 60 degreesC in the mixed film with some LC molecules.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

A mixed solution of poly(dihexylsilane) and 4'-pentyl-4-cyanobiphenyl (5CB) was spread on pure water. Surface pressure-area isotherm data and Brewster angle microscopy showed that a monomolecular stretching of this hydrophobic polysilane is performed with the assist of 5CB molecule.

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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DOI： 10.1295/koron.56.406

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Phenyl-substituted polygermane homopolymers (PhMeGe)(n) and copolymers with polysilanes (PhMeGe)(n)(PhMeSi)(m) are found to be excellent photoconductors with a well-defined mobility of about 10(-5) cm(2)/V s. (C) 1998 Elsevier Science S.A. All rights reserved.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOHN WILEY & SONS LTD  

Upon ultraviolet irradiation of polygermane copolymers of methylphenylgermylene/phenylgermyne units (PhMeGe)(n)(PhGe)(m) in air, the germanium-germanium bond in the copolymer film changed into a digermoxane chain, Laser flash photolysis of the copolymer film showed the intermediacy of polygermyl radicals generated by Ge-Ge bond homolysis, The XPS showed the formation of germanium carbide (GeC) and germanium dioxide (GeO2) upon heating the unirradiated and irradiated copolymer (PhMeGe)(n)(PhGe)(m) films, respectively, A relatively high-resolution micropattern of GeC/GeO2 was obtained by combining the photochemical and thermal properties of the copolymers of methylphenylgermylene/phenylgermyne units. (C) 1997 John Wiley & Sons, Ltd.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA LAUSANNE  

Upon ultraviolet irradiation of thin films of linear polygermanes in air, the germanium-germanium bond in thin films of polygermanes changed into digermoxane chains. The laser flash photolysis of the linear polygermane films showed the formation of polygermyl radicals generated by germanium-germanium bond homolysis as reactive intermediates during photodegradation. (C) 1997 Elsevier Science S.A.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Third-order nonlinear susceptibilities (chi((3))) for thin films of oligo- and polygermanes were measured in the range of 0.6-86x10(-12) esu. A measured chi((3)) of 86 x 10(-12) esu for a polygermane-polysilane random copolymer, coploy(methylphenylsilylene/methylphenylgermylene), was the largest ever reported for transparent polymers in the visible spectral region.

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Language：English   Publishing type：Research paper (scientific journal)  

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Publishing type：Research paper (scientific journal)  

DOI： 10.1002/adma.19950071110

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Language：Japanese   Publisher：Japanese Liquid Crystal Society  

As Brij 56 (a typical non-ionic surfactant consisting of polyoxyethylene cetyl ether) exhibits a lyotropic liquid crystalline nature in a water system, we used the lyotropic phase as a nanotemplate via a sol-gel reaction. Submicron-thick Brij 56/silica hybrid films were prepared from Brij 56/tetraethoxysilane precursors with various molar ratios onto glass or silicon substrates by spincast method. The resulting films were characterized by grazing-incidence small-angle X-ray scattering measurements, and transmission electron microscope observations. As a result, the films had ordered-nanostructures derived from the lyotropic phase of Brij 56. In particular, the nanostructures aligned perpendicular to the substrate in case that the weight content of Brij 56 in the hybrid film was equal to the amounts between a micellar cubic phase and a hexagonal phase.

DOI： 10.11538/ekitou.2015.0__PA17

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Language：Japanese   Publisher：THE JAPANESE LIQUID CRYSTAL SOCIETY  

<p> Organic/inorganic hybrid films were prepared onto substrates by spin-coating of mixtures of an amphiphilic block copolymer, polystyrene-block-poly(ethylene oxide) dib lock copolymer, and alkoxy titanium via evaporation-mediated direct templating process. After calcination of the resulting films, field emission-scanning electron microscope observations and grazing-incidence small-angle X-ray scattering measurements were performed. As a result, the calcinated films possessed the vertically aligned mesopores. The vertically aligned mesoporous titania films are used as a titania electrode in a dye-sensitized solar cell. Incident photon -to-current efficiency of the vertically -aligned mesoporous titania films have approximately 4 times improvement as compared to one of non-mesostructured titania films.</p>

DOI： 10.11538/ekitou.2014.0_PB13

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Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

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Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

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Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

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Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

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Language：Japanese   Publisher：The Society of Polymer Science, Japan  

DOI： 10.1295/kobunshi.55.904

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We prepared mixed monolayers of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) with low molecular weight compounds, 6-{4-[(4-hexylphenyl)azo] phenoxy}hexanoic acid (6Az5-COOH) and 4′-pentyl-4-cyanobiphenyl (5CB), by cospreading on pure water from chloroform solutions. The resulting films were characterized by π - A isotherms and transferred onto mica substrates. The morphologies of the transferred films were evaluated by atomic force microscope. It was confirmed that hydrophobic PS block in PS-b-P4VP was spread with the assist of low molecular weight compounds as indicated by π - A isotherm and AFM. In the case of PS-b-P4VP/5CB hybrid, the highly regular dot array pattern of surface micelles grew with increasing surface pressure from an initially smooth monolayer. The various compositions of block copolymer segments provided the variation of the dot spacing and height in the nano dot array patterns of the PS-e-P4VP/5CB hybrids. On the other hand, PS-b-P4VP/6Az5-COOH hybrid exhibited the striped patterns with the both blocks spreading on water monomolecularly.

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