2021 Fiscal Year Final Research Report
Long-range ordered structure and 2D-Ising like critical behaviors induced by salts in organic solvent solutions
Project/Area Number |
18K03571
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Research Category |
Grant-in-Aid for Scientific Research (C)
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Allocation Type | Multi-year Fund |
Section | 一般 |
Review Section |
Basic Section 13040:Biophysics, chemical physics and soft matter physics-related
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Research Institution | Doshisha University |
Principal Investigator |
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Project Period (FY) |
2018-04-01 – 2022-03-31
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Keywords | 臨界現象 / 相分離 / 自己組織化 / ソフトマター / 溶媒和 / 中性子散乱 / 動的特性 |
Outline of Final Research Achievements |
Small-angle neutron scattering (SANS), static light scattering (SLS), and dynamic light scattering (DLS) experiments were performed to clarify the effect of antagonistic salts on the critical phenomena of water/organic solvent mixtures. SANS and SLS results showed that antagonistic salts induce a highly order structure, so-called "charge-density-wave structure", in water/2,6-dimethylpyridine, water/2-butoxyethanol, water/acetonitrile mixtures. Furthermore, it was found that the critical universality changed from 3D Ising to 2D Ising with the addition of salt in these mixed solutions, On the other hand, it was also clarified that the dynamic properties of the solution obtained by DLS are not affected by the salt. In addition, the Intramolecular interaction in the "highly ordered concentration fluctuation phase" was observed by NMR, and it was suggested that the intramolecular interactions between water and organic solvent do not change significantly even in the presence of salts.
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Free Research Field |
ソフトマター物理学
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Academic Significance and Societal Importance of the Research Achievements |
従来、溶液中におけるイオンの効果はデバイ長(約0.7nm)程度で遮蔽されるため、高分子や界面活性剤を含まないシンプルな有機溶媒水溶液中で10nmを超える大きな構造が誘起されることはないとされてきた。また、ソフトマターの臨界挙動は、平均場的な振舞い(長距離相互作用に起因する臨界現象)を示す一部の高分子や界面活性剤系を除き、ほとんどが3次元Ising臨界普遍性に従うとされてきた。本研究により、いくつかの有機溶媒水溶液系において上記の常識を打ち破る知見が得られた。本成果は、電荷を含むソフトマターの自己組織化のメカニズムと相転移・臨界現象の本質をより深く理解する上で基礎となる。
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