Crystallization of neutral poly(3-methylthiophene)

Summary form only given. Dedoped poly(3-methylthiophene), synthesised by chemical oxidation with ferric chloride in acetonitrile, shows dime broad wide angle X-ray scattering peaks indicating a loose crystallization in the hexagonal system of coiled chains formed by syn coupling of thiophene rings (according to F. Garnier et al., J. Mater. Sci. 20 (1985) 2687). An enhanced crystallization occurs by prolonged thermal annealing at temperatures beyond 130/spl deg/ C. After annealing at 400/spl deg/ C and slow cooling to room temperature the wide angle X-ray diffraction diagram shows six intense sharp peaks. As indicated by differential scanning calorimetry curves, the crystallization or recrystallization is enhanced by softening of the amorphous or loosely crystallized domains, respectively. By increasing the annealing temperature the sharp wide angle X-ray diffraction peaks develop on expense of the broad wide angle X-ray scattering peaks. Probable chain conformation and packing are discussed based on a powder X-ray diffraction pattern simulation method.