Electroresponsive behavior of gelatin/alginate semi-interpenetrating polymer network membranes under direct-current electric field

Novel gelatin/alginate semi-interpenetrating polymer network (semi-IPN) membranes were prepared by the introduction of linear alginate into a crosslinked gelatin hydrogel network, and their swelling properties and electroresponsive behavior were studied. The results indicated that the water take-up ability of the semi-IPN membranes increased with the increasing alginate content within the network. The semi-IPN membranes swollen in a neutral NaCl solution bent toward the cathode under non-contact dc electric fields, and their bending speed and equilibrium strain increased with the increasing of applied voltage and the alginate content within the hydrogel networks. In addition, the effect of crosslinker concentration of glutaraldehyde on the bending behavior has been studied. The equilibrium strain decreased as the GA concentration increased. By changing the direction of the applied potential cyclically, the semi-IPN hydrogel membranes exhibited good reversible bending behavior. The bending of the semi-IPN hydrogel membranes was initially explained by a bending theory of polyelectrolyte hydrogel based on the change of osmotic pressure due to the ion concentration difference between the inside and the outside of the hydrogel.