Electrosensitive polymer gels: Controlling size and shape by means of red–ox processes – outlook and prospects

Among stimuli–responsive polymer gel materials, those that are electrosensitive have recently attracted burgeoning research interest. In particular, electrosensitive hydrogels characterized by rapid and reversible volume and/or shape transition resulting from redox state changes are in increasing demand. This feature makes hydrogel materials much more attractive and has opened up new possibilities for their applications, e.g. in the construction of electrochemical actuators, micropumps, microvalves, artificial muscles, soft robots, and advanced drug delivery systems. In this review paper, we focus on one group of electroresponsive gels – those that undergo a volume phase transition or shape change in response to a change in oxidation state of the gel component. The number of articles on such materials is rather small, and in our view the field remains largely underexplored. Herein we review the mechanisms that have been shown to underlie this kind of electrosensitivity and present particular examples of macrogels, microgels, and thin gel layers anchored to conducting surfaces.