The Mediated Electrodeposition of Polypyrrole on Aluminium Alloy

Abstract

The direct electrodeposition of conjugated polymers onto active metals such as aluminium and its alloys is complicated by the concomitant oxidation of the metal that occurs at the positive potential required for polymer formation/deposition. We have developed an approach that uses electron transfer mediation to reduce the deposition potential of polypyrrole on aluminium and aluminium alloy by nearly 500 mV, permitting film deposition from aqueous solution with nearly 100% current efficiency. The mediator used in this initial work was 4,5-dihydroxy-1,3-benzenedisulfonate (DHBDS, disodium salt), which also served as the dopant or counter ion in the polymer. To better understand the mediation process, a series of substituted benzene compounds have been explored for their mediating properties. From these studies, we conclude that both the hydroxyl and the sulfonate functionalities of DHBDS appear to play a role in the mediated electrodeposition at aluminium alloy. New mediators for the electrodeposition of polypyrrole on Al alloy are suggested.