Abstract
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 (Cpx*) as the catalysts. The complexes are Ln(CH2SiMe3)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 AliBu3. For the St polymerization, a high activity up to 3.1 × 106 g of polymer molLn−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 × 106 g of copolymer molSc−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.
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Acknowledgments
This work was financially supported by the National Natural Science Foundation of China (Nos. 20974014, 21274012, 21322401 and 21774014) and the 111 project (No. B07012).
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Syndiotactic Polymerization of Styrene and Copolymerization with Ethylene Catalyzed by Chiral Half-sandwich Rare-earth Metal Dialkyl Complexes
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Peng, DQ., Yan, XW., Zhang, SW. et al. Syndiotactic polymerization of styrene and copolymerization with ethylene catalyzed by chiral half-sandwich rare-earth metal dialkyl complexes. Chin J Polym Sci 36, 222–230 (2018). https://doi.org/10.1007/s10118-018-2060-8
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DOI: https://doi.org/10.1007/s10118-018-2060-8