Supramolecular Controlled Pseudo-LCST Effects of Cyclodextrin-Complexed Poly(ionic liquids)

We investigated the complexation of monomeric 1-butyl-3-vinylimidazolium bis(trifluoromethylsulfonyl)imide ([bvim][Tf₂N]) with different cyclodextrins (CDs) in water. Furthermore, we discovered that the poly([bvim][Tf₂N]) 1 showed a pseudo-LCST (lower critical solution temperature) effect in the presence of CD. It was shown that the CD ring complexates only the polymer anion and slips off at higher temperature where the poly(ionic liquid) becomes insoluble in water. We were encouraged to prove this effect by turbidity measurements, microcalorimetric titrations, dynamic light scattering, and enzymatic scission of the CD.