An investigation of the effect of pyridine derivatives on the oxidative polymerization process of 2,5-dimercapto-1,3,4-thiadiazole and its disulfide dimer

The effects of pyridine and several derivatives (3-chloropyridine and lutidine) on the redox reactions of 2,5-dimercapto-1,3,4-thiadiazole (DMcT) and the disulfide dimer of DMcT have been examined using cyclic voltammetry and UV - vis spectroscopy. In the presence of these bases, the oxidative coupling reactions of DMcT and its disulfide dimer to give a disulfide-containing polymer are facilitated, presumably due to proton-transfer processes with the bases. The potentials at which the oxidative polymerization and reductive depolymerization occur in the presence and absence of such proton transfer reagents are discussed. Also, it is observed that the oxidation of DMcT is facilitated in the presence of DMSO or NMP. The relevance of these results to the possible use of DMcT/polyaniline composite materials as a cathode material in secondary lithium batteries is discussed, especially with regard to the potentials at which the various redox processes can occur.