Living syndiospecific polymerization of propylene with sterically encumbered titanium complexes activated by MMAO

doi:10.1039/c4py00813h

CORC > 化学研究所 > 中国科学院化学研究所

	Living syndiospecific polymerization of propylene with sterically encumbered titanium complexes activated by MMAO
	Long, Ying-Yun 1; Wang, Yong-Xia 1; Li, Bai-Xiang 1; Li, Yan-Guo 1; Li, Yue-Sheng 1,2
刊名	POLYMER CHEMISTRY
	2014-11-21
卷号	5 期号:22 页码:6510-6522
ISSN号	1759-9954
DOI	10.1039/c4py00813h
英文摘要	A series of sterically encumbered (salicylaldiminato)(beta-enaminoketonato) titanium complexes [3-Bu-t-2-OC6H3CH=N(C6F5)][RNvC(CF3)CHC(Bu-t)O] TiCl2 [1a: R = Ph, 1b: R = C6H4F(p), 1c: R = C6H4Cl(p), 1d: R = C6H4Br(p), 1e: R = C6H4Br(o)] were synthesized and tested to be efficient catalysts for syndiospecific polymerization of propylene in the presence of modified methylaluminoxane at room temperature. The introduction of a bulky bromine atom ortho to the imine nitrogen of the beta-enaminoketonato ligand not only successfully improved the pentad syndiotacticity (rrrr) of the resulting polypropylenes from 88.5% to 97.2%, but also provided better protection of the active site from attack of free AlR3 or monomers and thus contributed to the living polymerization nature, while keeping high catalytic activity. More importantly, compared with the famous pentafluorinated FI-Ti/MAO catalyst system, the sterically congested complex 1e with the bromine atom ortho to a N-aryl group displayed almost two times higher catalytic activity (14.5 vs. 28.0 kg mol(-1) h(-1)), producing polypropylenes with even higher pentad syndiotacticity (rrrr = 97.2% vs. 96.0%) and similar narrow molecular weight distributions (Mw/Mn = 1.12-1.26). In addition, the polymerization proceeded with a different monomer insertion mode of 1,2-insertion and a similar chain-end control mechanism. Quantitative C-13 NMR spectra revealed that polymers with various stereo structures ranging from highly syndiotactic and regioregular to atactic and regio-irregular polymers at different reaction temperatures were achieved, and the probable formation routes were proposed. The percentage of regio-irregularities of the monomer sequence arising from 2,1-insertion and 3,1-enchainment increased with the rise of reaction temperature.
语种	英语
出版者	ROYAL SOC CHEMISTRY
WOS记录号	WOS:000343703900015
内容类型	期刊论文
源URL	[http://ir.iccas.ac.cn/handle/121111/51341]
专题	中国科学院化学研究所
通讯作者	Li, Yue-Sheng
作者单位	1.Chinese Acad Sci, Changchun Inst Appl Chem, State Key Lab Polymer Phys & Chem, Changchun 130022, Peoples R China 2.Tianjin Univ, Sch Mat Sci & Engn, Tianjin 300072, Peoples R China
推荐引用方式 GB/T 7714	Long, Ying-Yun,Wang, Yong-Xia,Li, Bai-Xiang,et al. Living syndiospecific polymerization of propylene with sterically encumbered titanium complexes activated by MMAO[J]. POLYMER CHEMISTRY,2014,5(22):6510-6522.
APA	Long, Ying-Yun,Wang, Yong-Xia,Li, Bai-Xiang,Li, Yan-Guo,&Li, Yue-Sheng.(2014).Living syndiospecific polymerization of propylene with sterically encumbered titanium complexes activated by MMAO.POLYMER CHEMISTRY,5(22),6510-6522.
MLA	Long, Ying-Yun,et al."Living syndiospecific polymerization of propylene with sterically encumbered titanium complexes activated by MMAO".POLYMER CHEMISTRY 5.22(2014):6510-6522.