Chemical and Electrochemical Polymerization of Thiophene Derivatives

Abstract

Abstract The synthesis and some physical properties of polymers containing the thiophene ring are described. The polymerization of 3-phenylthiophene (1), 2-phenvi-thiophene (2). 2,5-diphenylthiophene (3), 2-(2-thienyl) pyridine (4) and 3,6-bis(2-thienyl)pyridazine (5) under electrochemical and chemical conditions are reported. The monomers were prepared by the nickel or palladium catalyzed cross-coupling reactions and were electrochemically polymerized using galvanostatic conditions (platinum electrodes) or chemically polymerized by oxidation with iron trichloride. The effect of monomer concentration, electrolyte and solvent were studied. From the examined polymers only poly(3-phenylthiophene) showed significant properties, considering morphology and conductivity. The other polymers gave mainly powder or porous films with low conductivity. The thermogravimetry analysis of poly (3-phenylthiophene) showed a wide temperature range of thermal stability, only over 450°C considerable weight loss was observed. Scanning electron microscopy (SEM) of samples obtained under different conditions demonstrated the dependence of the morphology upon monomer structures, nature of the dopant and synthetic route employed.