Highly trans-1,4-stereoselective coordination chain transfer polymerization of 1,3-butadiene and copolymerization with cyclic esters by a neodymium-based catalyst system

Abstract

trans-1,4-Selective coordination chain transfer polymerization of 1,3-butadiene was achieved by using a Nd(Oi-Pr)₃/Mg(n-Bu)₂ catalyst, affording polybutadienes having high trans-1,4 contents (ca. 96%), moderate molecular weight (M_n = 1.0–2.3 × 10⁴), and narrow polydispersity (M_w/M_n ∼ 1.7). In the system, Mg(n-Bu)₂ acted as both a co-catalyst and a chain transfer agent, and the calculated transfer efficiencies of Mg(n-Bu)₂ were 27–34%. The produced living polybutadiene could further initiate the ring-opening polymerization of ε-CL/lactide to give TPB-b-PCL/PLA copolymers in a controlled fashion. The crystalline amphiphilic copolymers (TPB-b-PCL/PLA) were subsequently applied to investigate their self-assembly behavior by adding a selective solvent into a polymer/co-solvent solution. The polymer plates composed of a crystallized TPB core and PCL/PLA brushes were obtained by the crystallization-driven self-assembly. Moreover, the morphology of the polymers underwent change from nano-sized plates to micro-sized plates with increasing addition of the selective solvent.