REACTIVE GROUPS ON POLYMER-COATED ELECTRODES, 7 NEW ELECTROGENERATED ELECTROACTIVE POLYTHIOPHENES WITH DIFFERENT PROTECTED CARBOXYL GROUPS

By the protection of the carboxyl group of 3-thiopheneacetic acid with differently substituted benzyl groups a series of new thiophene deriv atives were synthesized. While 3-thiopheneacetic acid is not electropo lymerizable, the new obtained monomers can be easily electrooxidized t o form stable electroactive polymers. The electrochemical characteriza tions show that the substitution of the benzyl groups exerts little ef fect on the electropolymerization process and that the obtained polyme rs exhibit the typical properties of polythiophene derivatives, e.g., odor behavior and electrochromism. SEM studies show that all synthesiz ed monomers possess a very good film formability and the resulting pol ymers exhibit a rather compact and homogeneous morphology on the Pt el ectrodes also containing scattered particles. Using p-nitrobenzyl-prot ected polymer as an illustrative example, it was demonstrated that the used protecting group can be easily split off in the solid state and the desired reactive carboxyl group can be produced on the polymer sur face. Therefore, through the protection of the carboxyl group, the ele ctropolymerization and the following removal of the protecting group, a new type of polymer matrix material with reactive carboxyl groups wa s simply prepared by using commercially available 3-thiopheneacetic ac id monomer.