Reversible coordinative chain transfer polymerization of isoprene and copolymerization with ε-caprolactone by neodymium-based catalyst

Coordinative chain transfer polymerization (CCTP) of isoprene was investigated by using the typical Ziegler-Natta catalytic system [Nd(Oi-Pr)(3)/Al(i-Bu)(2)H/Me2SiCl2] with Al(i-Bu)(2)H as cocatalyst and chain transfer agent (CFA). The catalyst system exhibited high catalytic efficiency for the reversible CCTP of isoprene and yielded 6-8 polymer chains per Nd atom due to the high chain transfer ability of Al(i-Bu)(2)H. The narrow molecular weight distribution (M-w/M-n = 1.22-1.45) of the polymers, the good linear relationship between the M-n and yield of the polymer, and the feasible seeding polymerization of isoprene indicated the living natures of the catalyst species. Moreover, the living Nd-polyisoprene active species could further initiate the ring-opening polymerization of polar monomer (epsilon-caprolactone) to afford an amphiphilic block copolymer consisting of cis-1,4-polyisoprene and poly(epsilon-caprolactone) with controllable molecular weight and narrow molecular weight distribution. (C) 2012 Elsevier Ltd. All rights reserved.