Analytical Sciences

Specific Solvation of Benzyl Methacrylate in 1-Ethyl-3-methylimidazolium Bis(trifluoromethanesulfonyl)amide Ionic Liquid

Masaru MATSUGAMI,*1 Kenta FUJII,*2 Takeshi UEKI,*3 Yuzo KITAZAWA,*4 Yasuhiro UMEBAYASHI,*5 Masayoshi WATANABE,*4 and Mitsuhiro SHIBAYAMA*2

*1 Faculty of Liberal Studies, Kumamoto National College of Technology, 2659-2 Suya, Koshi, Kumamoto 861-1102, Japan
*2 Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
*3 Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan.
*4 Department of Chemistry and Biotechnology, Yokohama National University, 79-5 Tokiwadai, Hodogaya, Yokohama 240-8501, Japan.
*5 Department of Chemistry, Faculty of Sciences, Kyushu University, Hakozaki, Higashi, Fukuoka 812-8581, Japan.

It has been established that poly(benzyl methacrylate) in a room-temperature ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([C₂mIm⁺][TFSA⁻]), exhibits lower critical solution temperature (LCST)-type phase separation. In this work we investigated the solvation structure of benzyl methacrylate monomer in the ionic liquid by using high-energy X-ray diffraction with the aid of a molecular dynamics simulation. It was found that the C₂mIm cation orderly distributes above and below a benzyl group within benzil methacrylate (BnMA), while the TFSA anion distributes around the equatorial position of the benzyl group where no cation distribution is found, with a weak interaction between TFSA and BnMA. The relationship between specific solvation and the LCST phase separation mechanism was considered at the molecular level.

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