Copolymerization of Styrene Derivatives witb Gadolinium Catalyst System

Abstract

Copolymerization of Styrenes was carried out with Gd (OCOCCl₃) ₃- (iso-Bu) ₃Al-Et₂AlCl in hexane at 50°C under N₂. As monomers styrene (St), p-chlorostyrene (PCS), p-methylstyrene (PMS), and p-methoxystyrene (PMOS) were used. The copolymer composition was analyzed by ¹³C NMR to examine the monomer reactivity ratios by the Fineman-Ross method. The values of the monomer reactivity ratios were r₁=0.72 and r₂=1.25 for the St (M₁) /PCS (M₂), r₁=0.38 and r₂=0.51 for St (M₁) /PMS (M₂), and r₁=0.55 and r₂=1.07 for St (M₁) /PMOS (M₂). Hammett plot of r₂ showed a positive line slope of ρ=2.15. Comequently, this result suggests that the mechanism of polymerizatio is apparently different from that by the Ziegler catalyst based on titanium where ρ=-0.95. An orbital level of Gd (OCOCCl₃) ₃ may control polymerizability of styrenes through the donatio and back-donation processes. Steric hindrance of asubstituted styrenes may decrease the polymerizability.