Copolymerization of 4-methylpentene-1 and styrene with TiCl3 and iBu3Al and the copolymer structure

Copolymers of 4-methylpentene-1 and styrene were prepared (TiCl₃-AliBu₃, 70°) and their structure investigated. Monomer reactivity ratios calculated from the copolymer compositions were found to be 3·92 and 0·98. Comparison of the i.r. spectra of copolymers thus prepared and of isotactic homopolymers (poly-4-methylpentene-1 and polystyrene) allowed some estimation of monomer distribution in copolymers of different composition; this estimation for styrene units was based on band intensities at 565, 1084 and 985 cm⁻¹, and for 4-methylpentene-1 units on band intensity at 997 cm ⁻¹. These data show the copolymers of 4-methylpentene-1 and styrene to have random structure, and to be described by statistic relationships corresponding to r₁r₂ ≈ 1. Possible reasons for discrepancies between r₁r₂-values from compositional studies and those obtained from i.r. data are discussed.