Electrochemically switchable surfaces using polymer brush-grafted conducting polymer films

Abstract

We demonstrate an electrochemical switching of conformation of surface-bound polymer brushes, by grafting environmentally sensitive polymer brushes from an electrochemically-active conducting polymer (ECP). Using atom transfer radical polymerization (ATRP), we grafted zwitterionic polymer brushes, poly(3-(methacryloylamino)propyl)- dimethyl(3-sulfopropyl)ammonium hydroxide) (MPDSAH), from a surface initiated poly(pyrrole-co-pyrrolyl butyric acid) film. The changes in ionic solution composition in electrical double layer at the surface resulting from oxidation and reduction of the ECP trigger a switch in conformation of surface-bound poly(MPDSAH), demonstrated here by electrochemical impedance spectroscopy (EIS). The switch is also dependent upon temperature. We speculate that the synergistic combination of properties embodied in these "smart" materials may find application in electrochemical control of surface wetting and of interaction with biomolecules and living cells.