Dynamically heterogeneous structure from liquid to glass in crystalline and non-crystalline aqueous solutions

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K05522
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Biological physics/Chemical physics/Soft matter physics
• Research Institution: Tokai University
• Principal Investigator: Shinyashiki Naoki 東海大学, 理学部, 教授 (00266363)
• Co-Investigator(Kenkyū-buntansha): 八木原 晋 東海大学, 理学部, 教授 (40191093)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: 誘電緩和 / 水溶液 / ガラス転移 / 氷 / 高分子 / ゼラチン / 協同運動 / 階層構造

Outline of Final Research Achievements

In this study, the cooperative molecular dynamics of polymer or protein, ice, and uncrystallized water in partially crystallized water mixtures with various proteins and polymers were investigated by means of broadband dielectric spectroscopy (BDS). Three relaxation processes originated from polymer or protein, ice and uncrystallized water were observed at temperatures ranging from immediately below the crystallization temperature, Tc. Below approximately 180 K, relaxation process of ice separates into two or more processes. In partially crystallized mixtures, the relaxation process of uncrystallized water in an uncrystallized phase with polymer or protein and the alpha process of polymer in the uncrystallized phase were observed in 40 and 50 wt % polymer-water mixtures. For mixtures with 30 wt % polymer or less, the relaxation process is attributed not only to the alpha process of polymer but also to interfacial polarization.

Free Research Field

数物系科学

Academic Significance and Societal Importance of the Research Achievements

従来得られてきた、氷結しない水溶液の分子運動に関する普遍性・物質依存性に関する知見を、他ではほとんど行われていない氷結水溶液の誘電緩和現象に拡張した。その結果、水の緩和時間の温度依存性の特異的挙動、溶質のガラス転移温度と水分子運動の関係などを、氷結した水溶液で解明した。さらに、水溶液中の氷の分子運動による緩和の特徴を、ゼラチン、球状たんぱく質、高分子水溶液で明らかにした。
本研究成果により、低温で水や氷の分子運動をコントロールできる技術が得られる可能性を示した。分子運動速度は物質の経時変化速度を直接左右するため、医療における低温臓器保存、食品の低温・乾燥保存、素材開発などへの利用が期待される。