SYNTHESIS AND ELECTRONIC-PROPERTIES OF POLY((E,E)-[6.2]-(2,5)THIOPHENOPHANE-1,5-DIENE)

Cationic cyclopolymerization of (E,E)-[6.2]-(2,5)thiophenophane-1,5-di ene (2) gave polymer 3 which has bridged thiophene rings pendant to th e polymer backbone. The structural, thermal, and electronic properties of polymer 3 were compared to those of its benzene analogue (1) and i ts nonbridged analogue poly (2-vinylthiophene) (5). The onsets of ther mal degradation for polymers 3 and 5 under helium were 425 and 382-deg rees-C, respectively. Polymer 3 exhibited conductivity in the 10(-3)-1 0(-4) S/cm range when exposed to iodine vapor, four orders of magnitud e higher than for 5 treated in the same manner. Apparent energies of a ctivation for conductivity in iodine saturated polymers 3 (0.57 eV) an d 5 (0.61 eV) were calculated from conductivity temperature dependence measurements. Conductivity parameters for iodine saturated 3 show bot h a higher level of conductivity and weaker temperature dependence tha n for the corresponding cyclopolymer 1 which has benzene rather than t hiophene moieties, suggesting that greater charge generation occurs in 3, due to the lower oxidation potential of the thiophenophane repeat units. Differences in conductivity behavior for iodine saturated polym ers 1, 3, and 5 are discussed in terms of both charge generation and m obility. (C) 1994 John Wiley & Sons, Inc.