Thermal/Light Dual-Activated Shape Memory Hydrogels Composed of an Agarose/Poly(acrylamide-<i>co</i>-acrylic acid) Interpenetrating Network

Abstract

In this work, an agarose/poly(acrylamide-co-acrylic acid) interpenetrating network hydrogel is prepared by the photopolymerization of acrylamide, acrylic acid, and N,N′-methylenebisacrylamide within agarose network at its gel state. The as-prepared hydrogel exhibits two independent kinds of shape memory effects. The thermal-activated shape memory behavior is attributed to the reversible coil-helix transformation of agarose, within the permanently cross-linked poly(acrylamide-co-acrylic acid) network; the light triggered shape recovery is driven by the dissociation of the complexes between carboxyl groups and Fe(III) ions, due to the photoreduction of Fe(III) to Fe(II) in the presence of citric acid. The versatile and simple strategy as presented here should be beneficial for the design of dual-activated shape memory hydrogels and foster their use in a number of fields such as biomaterials, soft robotics, smart actuators, and sensors.