Highly Regio- and Stereoselective Terpolymerization of Styrene, Isoprene and Butadiene with Lutetium-Based Coordination Catalyst
作者：Jian, ZB ,Tang, SJ,Cui, DM
关键字：block-copolymers; stereospecific polymerization; anionic-polymerization; conjugated dienes; complexes; precursors; ligand; methylaluminoxane; 1,3-butadiene; polybutadiene
By using the cationic lutetium allyl species (C5Me4–C5H4N)Lu(η3-C3H5)2 (1)/[Ph3C][B(C6F5)4], the copolymerization of isoprene (IP) with styrene (St) could be achieved in a full range of monomer feed ratios (10 mol %–90 mol %). The 13C NMR and DSC analyses, and the competitive polymerization ratios (rSt = 3.1 vs rIP = 23.9) clearly revealed that the obtained IP–St copolymers were multiblocked microstructure with high cis-1,4-polyisoprene (PIP) units (80%) and crystalline syndiotactic polystyrene (sPS) sequences, which was in contrast to the copolymerization behavior of butadiene (BD) and St with the same system that afforded only diblock copolymer. Strikingly, the terpolymerization of St with IP and BD via coordination mechansim was realized for the first time with high conversions (74–85%) and high activities (111–144 kg (molLu h)?1). The 13C NMR spectroscopic analysis indicated that the resultant terpolymers were composed of perfect sPS blocks, high cis-1,4-PIP units (77.7%) and almost pure cis-1,4-polybutadiene (PBD) sequences (97.5%) arranged in multiblocked mode. The insertion rate of styrene monomer in the terpolymer could be tuned swiftly by changing its feed ratio. DSC curves suggested that these multiblock terpolymers had continuously variable but single Tg and (or) Tm values, which was different from the triblock IP–BD–St terpolymer having two distinct Tg values (?105 and ?57 °C) and one high Tm value (265 °C). Such novel terpolymers could not be accessed by any other methods known to date.