Anomalous Kinetics of the Volume Phase Transition in Poly-N-Isopropylacrylamide Gels

Abstract

Extreme speeding-up of a large, discontinuous volume change at the volume phase transition of poly-N-isopropylacrylamide (PNIPA) gels has been realized. The gels prepared by the new method undergoes a shrinking transition faster by six orders of magnitude as compared with conventional PNIPA gels. The relaxation time of the volume shrinkage can be controlled from seconds to months on the same size of gels. A plausible mechanism of the dramatic speeding-up of the volume phase transition, as well as the mechanism of extremely slow kinetics of the conventional PNIPA gels are proposed.