(664a) Electrochemically Induced pH Changes Trigger Controlled Film Disassembly

Application of an electric potential to a polymer thin film-coated electrode can have a number of effects including film dissolution or swelling, which may hold promise for practical applications in drug delivery, biosensing, separations, and cell sheet engineering, among others. While polymer thin films may contain redox-responsive components, such as transition metal complexes or nanoparticles, films without redox-active materials may still be manipulated outside the typical ?working voltage range?. When sufficiently high voltages are applied to induce the oxidation or reduction of water (or dissolved species in the electrolyte), the local, or interfacial, pH may be purposefully altered. This strategy makes possible the manipulation of pH-responsive polymer films by controlling local pH while maintaining a constant bulk pH. In this way, sensitive biological species in the solution can be shielded from the local extreme pH conditions, in contrast to classic pH-responsive systems that require large bulk pH changes. Currently, we are modeling interfacial pH profiles and exploring the use of electrochemically induced pH changes for drug delivery, the generation of ultrathin free-standing films, and the manipulation of surface mechanical properties.