POLYMERIZATION AND POLYMER PROPERTIES OF (2-METHYL-5-TERT-BUTYLPHENYL)ACETYLENE - STERIC EFFECTS OF THE RING SUBSTITUENTS

(2-Methyl-5-tert-butylphenyl)acetylene (2Me5tBuPA) polymerized in the presence of MoCl5-n-Bu4Sn catalyst in 1,4-dioxane to give a high molec ular weight polymer (MBAR(w) 8x10(5). Not only MoCl5- but also WCl6-ba sed catalysts were effective. The polymer obtained was a dark brown so lid, soluble in organic solvents such as toluene and CHCl3, and formed a free-standing film by solution casting. The onset temperature of we ight loss of the polymer in air was 260-degrees-C. Its oxygen permeabi lity coefficient was 43 barrers, which is twice that of natural rubber . Differences from the results (usually lower molecular weight, not fi lm-forming, and thermally less stable) of both poly(phenylacetylene) a nd poly[(o-methylphenyl)acetylene] are attributable to the synergistic steric effect of the o-methyl and m-tert-butyl groups.