Copolymerization of 1-(trimethylsilyl)-1-propyne with disubstituted hydrocarbon acetylenes

Copolymerization of 1-(trimethylsilyl)-1-propyne (MeC ≡ CSiMe₃) with several aromatic and aliphatic disubstituted acetylenes (MeC ≡ CPh, n-BuC ≡ CPh, 2-octyne, and 4-octyne) were examined by using Ta and Nb catalysts. The TaCl₅–Ph₃Bi catalyst was effective in copolymerization with the aromatic acetylenes, whereas the NbCl₅–Ph₃Bi catalyst was preferable in copolymerization with the aliphatic acetylenes. The copolymerization products were not mixtures of homopolymers but copolymers. The relative reactivity of monomer tended to decrease with increasing steric effect of monomer: 2-octyne > MeC ≡ CSiMe₃ > 4-octyne > MeC ≡ CPh > n-BuC ≡ CPh. The copolymers of MeC ≡ CSiMe₃ with MeC ≡ CPh copoly(TMSP/PP)s] had high molecular weight (M _w > 1 × 10⁶), and provided thermally stable tough films. With increasing MeC ≡ CPh content of copoly(TMSP/PP), the oxygen permeability coefficient (P) decreased, while the separation factor (P/P) increased.