SURFACE FUNCTIONALIZATION WITH OXOMETALLATES ENTRAPPED IN POLYMERIC MATRICES .2. SUBSTITUTED PYRROLE-BASED ION-EXCHANGE POLYMERS

Two pyrrole monomers substituted at the nitrogen atom by appropriate alkyl ammonium chains were electropolymerized in acetonitrile onto electrode surfaces. The electropolymerization could not be performed successfully in aqueous solutions or in the presence of a large amount of water in CH3CN. The cyclic voltanmmetric behaviour of these films in various CH3CN+H2O mixtures and in other solvents was studied. These polymers have enhanced anion-exchange capacities. Another aim was to include oxometallates, which are known for their numerous catalytic properties. Inclusion of iso- and heteropolyanions in these polymers during their synthesis in the presence of these oxometallates appeared to be rather unfavourable and was accomplished better by a two-step technique: (i) synthesis of the polymer in "dry" acetonitrile and (ii) incorporation of the oxometallate by merely soaking the electrode (or cycling its potential in the appropriate potential domain) in an aqueous solution of the oxometallate. After stabilization, leakage of the dopant anion from the polymer matrices was completely suppressed. In such assemblies, the electronic and ionic conduction properties are separated from the catalytic properties by making the binding sites in the assembly less dependent on the redox properties of the basic polymer. Medium effects on these assemblies were studied. A strong micro-environment effect was observed. © 1990.