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

Abstract

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.