Abstract
Four pairs of acetylenic monomers: phenylacetylene/1-hexyne, phenylacetylene/trimethylsilyl-1 pentadiyne-1,4, 1-hexyne/trimethylsiloxy-3 propyne-1 and phenylacetylene/trimethylsiloxy-3 propyne, were copolymerized via a Ziegler-Natta pathway in the presence of Fe(CH3CH2CO2)(3)-AlEt(3), The values of the reactivity ratios, determined via either the Kelen-Tudos method or a non-linear regression method, suggest an almost exclusive terminal effect on the insertion of the monomers at the active site. Also, based on these values, the first three pairs show an alternating tendency without an azeotropic composition, whereas the last pair presents an azeotropic composition at 98% of phenylacetylene in the feed and a propensity towards the formation of homogeneous sequences. Copyright (C) 1996 Elsevier Science Ltd