Highly Syndioselective Coordination (Co)Polymerization of <i>para</i>-Chlorostyrene

Abstract

Chlorostyrene is difficult to polymerize due to its electron-withdrawing chlorine substituent. Herein, we report the polymerization of para-chlorostyrene (pCS) using rare-earth metal catalysts (Flu–CH2–Py)Ln(CH2SiMe3)2(THF)n (Ln = Y(1), Lu(2), and Sc(3)) performed fluently with high conversions to reach the highest activity at −25 °C and provide polymers with perfect syndiotacticity. The copolymerization of pCS with styrene is more facile and controllable to afford copolymers with narrow molecular weight distributions and variable pCS incorporations. Kinetics study reveals the monomer reactivity ratios of rpCS = 0.55 and rSt = 2.87, indicating the random sequence distribution, which is further confirmed by a 13C NMR spectrum analysis. Moreover, the terpolymerization of pCS with styrene and butadiene is realized with the highest pCS insertion rate of 9.3% and gives, for the first time, chlorine functionalized St–BD copolymers having high molecular weights, rrrr > 99% syndiotacticity for both PS and P(pCS) units, and high 1,4-regularity (73%) for polybutadiene units.