POLYMERIZATION OF (O-ALKYLPHENYL)ACETYLENES AND POLYMER PROPERTIES

(o-Alkylphenyl)acetylenes (alkyl: Et, n-Bu, n-C6H13, n-C8H17, and iso-Pr) polymerized in high yields with W and Mo catalysts. MoCl5-based catalysts, which are not very active to phenylacetylene (PA), exhibited high activity like the WCl6 counterparts. The weight-average molecular weights (M(w)BAR) of the polymers having o-n-alkyl groups were in the range 2 x 10(4)-55 x 10(4), being similar to or slightly higher than those of poly(PA), while the highest M(w)BAR value of poly(o-iso-Pr-phenylacetylene) [poly(iso-PrPA)] reached 1 x 10(6). The formed polymers were dark red, and had the structure [CH = C(C6H4-alkyl)]n. They were thermally more stable than poly(PA) according to the thermogravimetric analysis. The polymers with long o-n-alkyl groups were soluble in aliphatic solvents (e.g., hexane) unlike poly(PA), and their softening points were lower. Poly(o-iso-PrPA) was film-forming, and fairly gas-permeable (P(O2) 27 barrers, P(O2)/P(N2) 2.2).