Fully-reversible and semi-reversible coordinative chain transfer polymerizations of 1,3-butadiene with neodymium-based catalytic systems

Coordinative chain transfer polymerization (CCTP) of 1,3-butadiene was assessed by employing several traditional Ziegler-Natta type Nd-based catalytic systems. Both the types of alkylaluminum as CTA and chloride donor as third component significantly affected the chain transfer characteristic of the CCTP systems. Among the catalytic systems examined, Nd(OiPr)3/Al(iBu)2H/Me2SiCl2 and Nd(OiPr)3/Al(iBu)2H/Al2Et3Cl3 systems exhibited the highest catalytic efficiency, yielding 6-10 polymer chains per Nd atom in the presence of 20 equiv. CTA. Kinetic examination revealed that Nd(OiPr)3/Al(iBu)2H/Me2SiCl2 and Nd(OiPr)3/Al(iBu)2H/Al2Et3Cl3 catalytic systems proceeded with fully- and semi-reversible chain transfer reactions, respectively. Quantitative formation of polymers was observed in each step of the 1,3-butadiene seeding polymerization, indicating the living mode of the two catalytic systems. Moreover, the triblock copolymers, PBD-b-PIP-b-PBD and PBD-b-PIP-b-PCL, were successfully synthesized with Nd(OiPr)3/Al(iBu)2H/Me2SiCl2 catalytic system.