Preparation and characteristic of electric stimuli responsive hydrogel composed of polyvinyl Alcohol/Poly (Sodium maleate-co-sodium acrylate)

Maleic anhydride was used to preparare polyvinyl alcohol/poly (sodium maleate-co-sodium acrylate) hydrogels (PVA/poly(SMA-SAA)) by a repeated frost-defrost process because of its higher charge density and potential electric stimuli sensitivity. The bending angle was measured in a noncontact electric field using carbon as plate electrodes. It was found that the bending angle was dependent on various factors, including composition of hydrogel, concentration of NaCl solution, types of electrolyte solution, and electric voltage. It exhibited that the bending angle increased when the concentration of NaCl solutions and the electric voltages increased. An abnormal bending direction was observed and it was affected not only by the kinds of hydrogels, but also by the exterior variations. The hydrogel showed good reversibility in on-off electric field and could be a candidate for practical application. (C) 2007 Wiley Periodicals, Inc.