Novel pH-responsive hydrogels with gradient charge distribution

Abstract

A strategy for the preparation of smart polymer gels with gradient weak polyacid distribution that exhibit pH-induced bending/straightening behaviour is reported. Gradient distribution of acid units inside the gel sample is obtained by copolymerization of N-isopropylacrylamide with acrylic acid sodium salt between two surfaces with different degrees of hydrophobicity/hydrophilicity. The reversibility of pH-induced bending is demonstrated.