USE OF POLYTHIOPHENE AND POLY(THIOPHENE-3-ACETIC ACID) AS CHARGE-SELECTIVE FILMS FOR AMPEROMETRIC FLOW-CELL DETECTORS

A new method for preparing charge-selective polythiophene and poly(thiophene-3-acetic acid) films is described. The polymers were coated onto a micro-flow-cell electrode using constant current electrochemical polymerization. These polymer-modified electrodes exhibited charge-selective responses towards ascorbic acid, catechol and dopamine, when polymerized from solutions containing optimum amounts of water, Investigations by infrared and X-ray photoelectron spectroscopies showed that electron-rich hydroxy, carbonyl and carboxyl groups were responsible for polythiophene's charge-selective property. Whereas, poly(thiophene-3-acetic acid) is inherently charge-selective, and its charge-selective property was observed only when the porosity of the film was increased by the impeding effect of water on polymer growth during polymerization.