ELECTROPOLYMERIZATION OF CATIONIC AMPHIPHILIC PYRROLE DERIVATIVES ON ELECTRODES - EVIDENCE FOR ENVIRONMENTAL-EFFECTS ON REDOX POTENTIALS OFTRAPPED ANIONS

Amphiphilic (pyrrolylalkyl)ammonium monomers, differing in the size of their cationic polar headgroup -N+(CnH2n+1)3 (n = 1-4,6), have been s ynthesized and studied. Surfactant properties of these compounds have been examined. The monomer with n = 1 forms micelles in solution. All the other monomers do not lead to the formation of organized assemblie s. However, they disperse in pure water upon sonication and lead to th e formation of milky dispersions, from which monomer films are coated on an electrode surface and subsequently electropolymerized in an aque ous electrolyte. This process produces stable, electroactive cationic films which could incorporate bulky electroactive anions. The permeabi lities and anion-exchange properties of these poly(amphiphilic pyrrole ) films depend on the headgroup size of the monomer. Incorporation of electroactive anions could also be accomplished in one step, by electr opolymerization of monomer-anion mixtures coated on an electrode surfa ce. With the anthraquinonesulfonate anion, peak splitting of the cycli c voltammetry curve of the modified electrode studied in an aqueous el ectrolyte suggests a regular surface arrangement.