Synthesis of high molecular weight copolymer of styrene and butadiene bearing high 1,4‐cis butadiene unit from copolymerization with CpTiCl₃/methylaluminoxane catalyst

Abstract

Copolymerization of styrene (St) and butadiene (Bd) with CpTiCl 3 /methylaluminoxane (MAO) catalyst in the presence or absence of chloranil (CA) was investigated. The CpTiCl 3 /MAO catalyst showed a high activity for the copolymerization of St with Bd. The 1,4-cis contents in the Bd units for the copolymerization of St and Bd with the CpTiCl 3 /MAO catalyst was observed, and the 1,4-cis content was optimum at a MAO/Ti mole ratio of around 225. The effect of the polymerization temperature on the copolymerization was noted, as was the effect of the 1,4-cis microstructure in the Bd units for the copolymerization of St and Bd. The addition of CA to the CpTiCl 3 /MAO catalyst was found to influence the molecular weight of the copolymer. The high weight-average molecular weight copolymer (M w ϭ ca. 50 ϫ 10 4 ) consisting of mainly a 1,4-cis microstructure of Bd units (1,4-cis ϭ 80.0%) was obtained from the copolymerization with the CpTiCl 3 /MAO catalyst in the presence of CA (CA/Ti mole ratio ϭ 1) at 0°C.

Stereospecific sequential block copolymerizations of styrene and 1,3‐butadiene with a C5Me5TiMe3/B(C6F5)3/Al(oct)3 catalyst

“…Recent achievements in the stereospecific copolymerization of ST and BD with transition‐metal catalysts has provided alternative routes to improving the mechanical properties of these materials through the control of the cis selectivity of the PB segments 10–19. Unfortunately, none of these catalysts are able to effectively control the stereoregularity of the PS segments.…”