掲載種別：研究論文（学術雑誌）  

The samples investigated were prepared by seeking poly(ϵ-caprolactone) (PCL) films in seawater for the study of marine degradation processes. Raman mapping measurements in the low-frequency region and the C═O stretching region were used for investigating the strength of the CH···O═C hydrogen bonding and the changes in the crystallinity of PCL, respectively, in its marine degradation process. During the marine degradation of the PCL film, the amorphous parts of the film decomposed and flow away in the seawater. A band at around 60 cm-1 reflecting intermolecular CH···O═C hydrogen bonds showed a weakening of hydrogen bonds in the crystal structure of PCL. Three-dimensional (3D) Raman mapping developed by the C═O stretching region indicated that the marine degradation started from the surface of the annealed PCL film. However, 3D Raman mapping measurements in the low-frequency region showed no significant difference in the strength of the hydrogen bonding between a film surface and an inside after marine degradation of day 7. These findings suggest that the crystallinity changes mainly near the film surface, but changes in the strength of the hydrogen bonding occur both near the surface and inside of the PCL film.

DOI： 10.1021/acsapm.4c00621

Scopus

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担当区分：筆頭著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：Wiley  

Abstract

Raman spectra of water and supercooled water were measured in the temperature range of −6 to 18°C with every 2°C step. The obtained spectra were analyzed for the 3750–2850 and 400–100 cm⁻¹ regions by two‐dimensional correlation (2D‐COS) Raman spectroscopy. As previously reported, there are three bands at around 3620, 3420, and 3200 cm⁻¹ in the OH‐stretching region. These bands were assigned to the OH‐stretching modes of dangling (Dang) bonds of water, destructured, and structured water species, respectively. A pair of clear peaks appear in asynchronous 2D‐COS maps in the 3750–2850 cm⁻¹ region of Raman spectra of water developed using the spectra measured in the temperature ranges of −6 to 2°C, 0 to 8°C, and 8 to 18°C, and they are similar to each other, suggesting nonlinear (convex) temperature‐dependent increase and decrease of the two kinds of water species. A power spectrum calculated along the diagonal line in the synchronous spectrum in the −6 to 18°C range has a peak at 3171 cm⁻¹ with a broad shoulder at around 3400 cm⁻¹. These peaks at 3171 and 3400 cm⁻¹ may be assigned to the collective mode and its local mode of structured water, respectively. In the 400–100 cm⁻¹ region, there is a broad feature centered at 185 cm⁻¹ assigned to the intermolecular stretching mode of water molecule. Close inspection of the low‐frequency region by the baseline corrected spectra and the second derivative spectra shows that the broad feature consists of a major band at around 185 cm⁻¹ and a weak shoulder at around 150 cm⁻¹. We have assigned these two peaks at 185 and 150 cm⁻¹ to the structured and destructured water, respectively, based on the results of 2D‐COS and the comparison with the results of multivariate curve resolution‐alternative least squares reported by Hamaguchi et al. A hetero 2D correlation synchronous map between the 3750–3000 and 400–100 cm⁻¹ regions reveals that there is a cross peak between the structured water band at around 3200 cm⁻¹ and the 185 cm⁻¹ band, confirming that the 185 cm⁻¹ band comes from the structured water.

DOI： 10.1002/jrs.6444

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その他リンク： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/jrs.6444

担当区分：筆頭著者   出版者・発行元：AIP Publishing  

DOI： 10.1063/5.0071893

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その他リンク： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-21K05013/

担当区分：筆頭著者   記述言語：英語   出版者・発行元：社団法人 日本分析化学会  

DOI： 10.2116/analsci.19c011

DOI： 10.1039/d0cp03865b_references_DOI_Fow4PRZmf8rygqweelJLkFZIpO6

PubMed

CiNii Article

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その他リンク： https://link.springer.com/article/10.2116/analsci.19C011/fulltext.html

担当区分：筆頭著者   出版者・発行元：American Chemical Society (ACS)  

DOI： 10.1021/acs.jpca.9b09274

DOI： 10.3175/molsci.14.a0114_references_DOI_JD6ZusM7OHffgvMiPGH0tTpY9ZB

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開催年月日： 2020年 - 2020年

記述言語：日本語  

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