Electrochemical processing of the conducting polymer poly(SNS)

Oxidized poly(2,5-di-(2-thienyl)-pyrrole) [poIy(SNS)] films have been electrosynthesized on Pt from a 5 mM monomer and 0.1 M LiClO₂ + acetonitrile solution at constant anodic current density. The electrogenerated films follow a faradaic electrodissolution when subjected to a cathodic current in different LiClU₄ + acetonitrile media, giving solutions containing the reduced polymer. Deposits of oxidized poly(SNS) have been further obtained on a Pt electrode by a flow of an anodic constant current through a solution of the reduced and solved poly(SNS) in LiClO₄ + acetonitrile. These'electrodeposited films are partially soluble and electrosoluble. The yield of the electrodeposition process is lower than that of the further electrodissolution process. This fact is due to the presence of parallel reactions such as crosslinking and discharge of residual contaminants during the electrodeposition process. A careful purification, i.e. removal of the contaminants, closes the gap between the productivity of the consecutive electrodeposition and electrodissolution processes: 72% of the electrodeposited polymer is subsequently electrodissolved, showing that both processes are close to technological reversibility. This is the first time that a process envisaging such a possible electrochemical processability, where a polymer mimics the electrodissolution and electrodeposition of metals, is described.