Chemomechanical Motion of a Self‐Oscillating Gel in a Protic Ionic Liquid

Abstract

An autonomous swelling-deswelling oscillation of polymer gels in ahydrated protic ionic liquid (PIL) as aproton source for the Belousov-Zhabotinsky( BZ) reaction is presented. Methylammonium hydrogen sulfate ([maH + ][HSO 4 À ]) was employed as the PIL because it provides stable redox oscillation in the BZ reaction. Due to the significantly higher pK a for [maH + ][HSO 4 À ]t han those for conventional proton sources for the BZ reaction, chemomechanical oscillation can be expected under weaker acidic conditions.T he self-oscillating polymer was designed as at ernary random copolymer of N-isopropylacrylamide,N -(3-aminopropyl)methacrylamide, and the Ru(bpy) 3 moiety as ac atalyst for the BZ reaction. The copolymer exhibited spontaneous soluble-insoluble oscillation in hydrated [maH + ][HSO 4 À ]c ontaining NaBrO 3 and malonic acid. Macroscopic swelling-deswelling oscillation of the porous bulk gel prepared by covalently connecting microgel particles was also observed. À ]( 800 mm)containing NaBrO 3 (0.15 m)and MA (0.10 m)a t188 8C. Angewandte Chemie Communications