Access to High-Molecular-Weight Polyethylenes through High Temperature Ethylene Polymerization Catalysed by Ethylene-Bridged ansa-(3-R-Cyclopentadienyl)(Fluorenyl) Zirconocene Complexes
RESEARCH ARTICLE|Updated:2023-12-26
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Access to High-Molecular-Weight Polyethylenes through High Temperature Ethylene Polymerization Catalysed by Ethylene-Bridged ansa-(3-R-Cyclopentadienyl)(Fluorenyl) Zirconocene Complexes
Chinese Journal of Polymer ScienceVol. 42, Issue 1, Pages: 42-51(2024)
Affiliations:
Shanghai Key Laboratory of Functional Materials Chemistry and Laboratory of Organometallic Chemistry, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
Li, B.; Ma, H.; Huang, J. Access to high-molecular-weight polyethylenes through high temperature ethylene polymerization catalysed by ethylene-bridged ansa-(3-R-cyclopentadienyl)(fluorenyl) zirconocene complexes. Chinese J. Polym. Sci. 2024, 42, 42–51
Bo Li, Haiyan Ma, Jiling Huang. Access to High-Molecular-Weight Polyethylenes through High Temperature Ethylene Polymerization Catalysed by Ethylene-Bridged ansa-(3-R-Cyclopentadienyl)(Fluorenyl) Zirconocene Complexes[J]. Chinese Journal of Polymer Science, 2024, 42(1): 42-51. DOI: 10.1007/s10118-023-3034-z.
Li, B.; Ma, H.; Huang, J. Access to high-molecular-weight polyethylenes through high temperature ethylene polymerization catalysed by ethylene-bridged ansa-(3-R-cyclopentadienyl)(fluorenyl) zirconocene complexes. Chinese J. Polym. Sci. 2024, 42, 42–51DOI: 10.1007/s10118-023-3034-z.
Bo Li, Haiyan Ma, Jiling Huang. Access to High-Molecular-Weight Polyethylenes through High Temperature Ethylene Polymerization Catalysed by Ethylene-Bridged ansa-(3-R-Cyclopentadienyl)(Fluorenyl) Zirconocene Complexes[J]. Chinese Journal of Polymer Science, 2024, 42(1): 42-51. DOI: 10.1007/s10118-023-3034-z.DOI:
Access to High-Molecular-Weight Polyethylenes through High Temperature Ethylene Polymerization Catalysed by Ethylene-Bridged ansa-(3-R-Cyclopentadienyl)(Fluorenyl) Zirconocene Complexes
-(3-R-cyclopentadienyl)(fluorenyl) zirconocene and hafnocene complexes have been synthesized and characterized. Among them zirconocene complexes showed high catalytic activities toward the polymerization of ethylene at high temperatures. By adopting low Al/Zr ratios such as 125
polyethylenes with ultra-high molecular weights up to 2.86×10
characterized and investigated as catalyst precursors for the high temperature ethylene polymerization. Using methylaluminoxane (MAO) as the cocatalyst
zirconium complexes
1
−
5
bearing a bulky substituent on the 3-position of the cyclopendienyl ring showed high catalytic activities up to 1.48×10
7
g
PE
·mol
Zr
−1
·h
−1
toward the polymerization of ethylene and afforded polyethylenes with high molecular weights (1.49×10
5
−6.31×10
5
g/mol)
meanwhile exhibting great thermal stability at high temperatures up to 120 °C together with a long catalytic life time up to 2 h. By adopting low Al/Zr ratios
such as 125
polyethylenes with ultra high molecular weights up to 2.86×10
6
g/mol were obtained. It is worthy of noting that zirconium complexes
1
−
4
bearing a substituent with an aryl pendant showed temperature-dependent activities
which increased rapidly with the increase of polymerization temperature
thus weak interaction of the pendent aryl group with the cationic active center is proposed to account for the very low activities displayed at low temperatures. In contrast to zirconocene complexes
1
−
5
hafnocene complex
6
only displayed very low catalytic activities toward the polymerization of ethylene and afforded
polyethylenes with molecular weights ten times smaller than those obtained by zirconocene complexes
1
−
5
. Zirconocene complexes
1
−
5
were also able to catalyse the polymerization of propylene at high temperatures
but only afforded waxes with low molecular weights.
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