Grafting, Ionomer Composites, and Auto-doping of Conductive Polymers

The easy electrodeposition of poly(pyrrole) even when starting from N-derived pyrrole monomers has opened up a new field in the coating of electrodes by various specific molecules (electroactive, photo-sensitive, catalytic centres …). In order to overcome some difficulties due to the poly(pyrrole) matrix (instability upon cycling, inclusion of protons …) this method is now being extended to poly(derived-thiophenes). But new requirements have arisen specifically due to the severe conditions of electropolymerization of 3-derived thiophenes. The doping process of conductive polymers has been exploited to form interpenetrated composites in which the second polymer component is an ionomer acting as a macro-dopant of the conductive matrix. The quasi-immobilisation of the anionic dopants in these structures allows them to function as cation-exchangeable polymers with new applications in battery and water deionization. In connection with the immobilization of the dopant we present a new approach, the “auto-doped” polymers, in which the sulphonate dopant is grafted to the polymer via an alkyl linkage.