Characterization of electroactive behavior and of progress in developments and applications of ionic polymer gels

Polyelectrolyte gels are distinguished by enormous swelling capabilities under the influence of external physical or chemical stimuli. No other kind of material attains similar volume expansiveness., These properties make them most attractive candidates for a new generation of much greater thanpseudomuscularmuch less than actuators. In contrast to chemical stimulations which are able to trigger large in-toto deformations, weak electric fields can only induce considerable bending strains in ionic polymer gels when confined to direct electrical effects. This, of course, restricts their potential for technical applications. To characterize their chemo-mechanical and. electrical behavior and the underlying physico-chemical processes, experimental and theoretical findings are presented. Measurements of basic mechanical and electrical parameters on polyelectrolyte gels allow quantification of their electroactive responses, especially with respect to the direct effects of external electric fields on the Donnan potential inside the gels. Model calculations on the basis of a coupled chemo-electro-mechanical multi-field formulation are in good agreement with the experimental results. Although the emphasis of this study is given to various anionic and cationic gels of the polyacrylamide family, a new class of hydrogels based on the biopolymer chitosan is included. These natural polymers have excellent properties such as biocompatibility, biodegradability, non-toxicity etc. making them predestinate to biomedical. applications.