Molecular vibration and Boson peak analysis of glucose polymers and ester via terahertz spectroscopy

Junlan Zhong; Tatsuya Mori; Yasuhiro Fujii; Takanari Kashiwagi; Wakana Terao; Midori Yamashiro; Hidotoshi Minami; Manabu Tsujimoto; Teruhiko Tanaka; Hidehisa Kawashima; Junko Ito; Masashi Kijima; Masatoshi Iji; Makoto M Watanabe; Kazuo Kadowaki

doi:10.1016/j.carbpol.2019.115789

Molecular vibration and Boson peak analysis of glucose polymers and ester via terahertz spectroscopy

Carbohydr Polym. 2020 Mar 15:232:115789. doi: 10.1016/j.carbpol.2019.115789. Epub 2019 Dec 28.

Authors

Affiliations

¹ Graduate School of Life and Environment Sciences, University of Tsukuba, Japan. Electronic address: s1730112@u.tsukuba.ac.jp.
² Division of Materials Science, Faculty of Pure and Applied Sciences, University of Tsukuba, Japan.
³ Department of Physical Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu 525-8577, Japan.
⁴ System Platform Research Laboratories NEC Corporation, 34 Miyukigaoka, Tsukuba, Ibaraki 305-8501, Japan.
⁵ Division of Materials Science, Faculty of Pure and Applied Sciences, University of Tsukuba, Japan; Algae Biomass and Energy System (ABES) Research and Development Center, University of Tsukuba, Japan.
⁶ Algae Biomass and Energy System (ABES) Research and Development Center, University of Tsukuba, Japan.

PMID: 31952597
DOI: 10.1016/j.carbpol.2019.115789

Abstract

Complex permittivity spectra were obtained herein by performing broadband terahertz (THz) spectroscopy on cellulose, paramylon, and paramylon ester. Absorption peaks observed for cellulose and paramylon at approximately 3 THz are attributed to hydrogen bonds. In addition, a broad absorption peak around 2 THz was observed for all the polymers, demonstrating a general feature of polymer glasses derived from weak interatomic van der Waals forces. The boson peak was observed for cellulose and paramylon ester. The boson peak frequency for cellulose nearly equaled that for glassy glucose-a unit structure of the cellulose polymer. Additionally, the insensitivity of cellulose to the polymerization degree was consistent with recent results obtained via molecular dynamics simulations. In contrast, the boson peak frequency of paramylon ester was markedly smaller than that of cellulose. These results demonstrate the importance of hydrogen bonds as determinants of the boson peak frequency.

Keywords: Boson peak; Glucose ester; Glucose polymers; Terahertz spectroscopy; Vibrational density of states.