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《高分子科学(英文版)》 2018-02
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Syndiotactic Polymerization of Styrene and Copolymerization with Ethylene Catalyzed by Chiral Half-sandwich Rare-earth Metal Dialkyl Complexes

De-Qian Peng;Xin-Wen Yan;Shao-Wen Zhang;Xiao-Fang Li;Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology;  
The syndiotactic polymerization of styrene(St) and the copolymerization of St with ethylene(E) were carried out by using a series of chiral half-sandwich rare-earth metal dialkyl complexes(Cp~x*) as the catalysts. The complexes are Ln(CH_2SiMe_3)_2(THF)(1-4: Ln = Sc(1), Ln = Lu(2), Ln = Y(3), Ln = Dy(4)) bearing chiral cyclopentadienyl ligand containing bulky cylcohexane derivatives in the presence of activator and AliBu_3. For the St polymerization, a high activity up to 3.1 × 10~6 g of polymer mol Ln~(-1)·h~(-1) and a high syndiotactic selectivity more than 99% were achieved. The resulting syndiotactic polystyrenes(sPSs) have the molecular weights(Mn) ranging from 3700 g·mol~(-1) to 6400 g·mol~(-1) and the molecular weight distributions(Mw/Mn) from 1.40 to 5.03. As for the copolymerization of St and E, the activity was up to 2.4 × 10~6 g of copolymer mol Sc~(-1)·h~(-1)·MPa~(-1), giving random St-E copolymers containing syndiotactic polystyrene sequences with different St content in the range of 15 mol%-58 mol%. These results demonstrate that the bulky cyclopentadienyl ligands of the chiral half-sandwich rare-earth metal complexes effectively inhibit the continued insertion of St monomers into the(co)polymer chain to some extent in comparison with the known half-sandwich rare-earth metal complexes.
【Fund】: financially supported by the National Natural Science Foundation of China (Nos. 20974014 21274012 21322401 and 21774014);; the 111 project (No. B07012)
【CateGory Index】: O631.5;O643.36
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