Design of Ionic Liquid-Derived Polyelectrolyte Gels Toward Reversible Water Absorption/Desorption System Driven by Small Temperature Change
Suitably designed polyelectrolytes derived from tributyl-n-alkylphosphonium 3-sulfopropylmethacrylate-type ionic liquid (IL) monomers undergo a lower critical solution temperature (LCST)-type phase transition, and their transition temperature is a function of the alkyl chain length on the phosphonium cations. Based on this finding, we have successfully prepared chemically cross-linked polyelectrolyte gels, poly(IL) gels, to show the LCST-type phase change. The hydrated state of the prepared poly(IL) gels varied widely with temperature. They desorbed water by elevating the temperature only by a few degrees. Their transition temperature was finely controlled by mixing the composition of IL monomers with different alkyl chain lengths.