H. Kouzai et al., POLYMERIZATION AND POLYMER PROPERTIES OF (2-METHYL-5-TERT-BUTYLPHENYL)ACETYLENE - STERIC EFFECTS OF THE RING SUBSTITUENTS, Polymer bulletin, 33(3), 1994, pp. 301-307
(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.