Preparation Of High-performance Rare Earth Butadiene Rubber By Coordination Reversible Chain Transfer Polymerizatio

With the development of synthetic rubber,coordination chain transfer polymerization（CCTP）has been drawn much more attention.CCTP shows similar behaviors with traditional anionic polymerization,such as controllable molecular weight and chain ends modification of polymers,due to its rapid and reversible chain transfer characteristics.In addition,it also has the bulk selectivity compared to anionic polymerization,where a central metal produces multiple polymer chains simultaneously and boosts the efficiency of catalyst.In this paper,CCTP was applied to the traditional rare earth catalytic system.Cis-polybutadiene with controllable molecular weight was synthesized simply and efficiently.The effect of types of electron donors on catalytic system was investigated.The mechanism of polymerization using CCTP was also explored.Besides,polybutadienes with different end functional groups were also obtained by changing chain termination agents.1.The synthesis of polybutadiene by Nd（vers）₃/Al（i-Bu）₂H/Me₂Si Cl₂was investigated.The microstructures of polybutadiene synthesized by CCTP were studied.The polymerization mechanism was proposed based on the polymer microstructures.It was found that microstructures of most polymers were[CH₃CHCHCHCH₂-]at the beginning and end of the chains,indicating that the chain transfer happened quickly and the active center formed by alkylation reaction could not initiate monomer polymerization of CCTP.Additionally,the polymerization mechanism of CCTP was confirmed further by polybutadiene terminated with different small molecules.2.The effect of external nitrogen donor on Nd（vers）₃/Al（i-Bu）₂H/A/Al₂Et₃Cl₃system was studied.The ability of system to tolerate impurities was also evaluated.When the concentration of nitrogen-containing agent was 1%,the catalytic system was not sensitive to the type of N-donor.The catalytic activity and stereoselectivity were similar to the system without N-donor.This was also found in Nd-mediated CCTP system.Moreover,the Nd-based CCTP system can control polymerization well and showed good N-donor tolerance.