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

摘要

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/Me_2SiCl_2 and Nd(OiPr)_3/Al(iBu) _2H/Al_2Et_3Cl_3 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/Me_2SiCl_2 and Nd(OiPr)_3/Al(iBu)_2H/Al_2Et_3Cl _3 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/Me_2SiCl_2 catalytic system.