Electroresponsiveness of a positively charged thin hydrogel layer on an electrode surface

Positively-charged very thin gel layers were deposited on conducting surfaces by an electrochemically-induced free-radical polymerization method. This method allowed the formation of a uniform and compact layer. 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, an electroactive compound with two sulphonate groups that form a dianion in aqueous solutions (ABTS2−), was introduced into the layer to act as an additional cross-linker. The gel layer could be reversibly swelled and shrunk by electrooxidizing/electroreducing the ABTS2− linker.