ELECTROCHEMICAL POLYMERIZATION AND DEPOLYMERIZATION OF 2,5-DIMERCAPTO-1,3,4-THIADIAZOLE - QCM AND SPECTROSCOPIC ANALYSIS

Electrochemical oxidation of a dimercaptan, 2,5-dimercapto-1,3,4-thiad iazole (DMcT), to a polydisulfide (DMcT polymer) and electrochemical r eduction of the polydisulfide at a carbon electrode and an indium-tin oxide electrode have been studied in 0.1 M LiClO4-acetonitrile by mean s of an in situ electrochemical quartz crystal microbalance and in sit u spectroelectrochemistry, respectively. It is observed that the polym erization potential is more positive than the dimerization potential. Both the potentials at which DMcT dimer and BMcT polymer are formed ar e made more negative by the presence of a base. The potential at which the DMcT polymer is reductively depolymerized is also shifted in the negative direction in the presence of a base. The experiments also sho w that the DMcT polymer reacts with DMcT monomer under open-circuit co nditions. This results in dissolution of the polymer in the presence o f the monomer. The results also suggest that the product of the redox reaction is the DMcT dimer. Base is shown to hinder this reaction.