POLYMERIZATION OF TRAHYDROTHIOPHENIOMETHYL)-2-CYANO-5-METHOXYBENZENE DIBROMIDE - SYNTHESIS OF ELECTRONICALLY PUSH-PULL SUBSTITUTED POLY(P-PHENYLENE VINYLENE)S

The base-induced polymerization of trahydrothiopheniomethyl)-2-cyano-5 -methoxybenzene dibromide in aqueous acetonitrile yields a soluble pol yelectrolyte which may be thermally eliminated to give the electronica lly 'push-pull' substituted poly(2-cyano-5-methoxy-1,4-phenylene vinyl ene). Ultraviolet-visible and infra-red spectral studies showed produc tion of the conjugated polymer, with a band gap of ca. 2.6-3.0 eV (410 -480 nm) that varied somewhat as a function of elimination conditions. Elemental analysis indicates some retention of tetrahydrothiophenium side groups in the polyelectrolyte polymer, despite the use of a varie ty of elimination conditions. The retention of side chains in this syn thesis is possibly due to a significant degree of irregularity in the positions of the cyano and methoxy substituents in the eliminated poly mer, resulting from non-regioselectivity in this polymerization. This reaction demonstrates the potential in the Wessling process for polyme rization of p-xylylenes that have electronically very asymmetric ('pus h-pull') substitution patterns.