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Copolymerization of Ethylene and 1,7‐Octadiene, 1,9‐Decadiene with Zirconocene Catalysts
Author(s) -
Naga Naofumi,
Imanishi Yukio
Publication year - 2002
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/1521-3935(200211)203:15<2155::aid-macp2155>3.0.co;2-7
Subject(s) - copolymer , ethylene , cyclopentadienyl complex , catalysis , polymer chemistry , chemistry , metallocene , polymerization , organic chemistry , polymer
Abstract Copolymerizations of ethylene and 1,7‐octadiene (OD) and 1,9‐decadiene (DD) were investigated with various non‐bridged and bridged zirconocene catalysts using methylisobutylaluminoxane as a cocatalyst. The resulting copolymers were extracted with boiling o ‐dichlorobenzene (ODCB), and the structure of the boiling ODCB‐soluble part was studied by 1 H, 13 C NMR and DEPT (distortionless enhancement of polarization transfer) spectroscopy. In the case of ethylene/OD copolymerization, the ligand structure of the zirconocene catalysts strongly affected the propagation mode of OD. The zirconocene catalysts having cyclopentadienyl or pentamethylcyclopentadienyl ligands gave copolymers having 1‐hexenyl and 1,3‐disubstituted cycloheptane units, derived from 1,2‐addition propagation and addition–cyclization propagation of OD, respectively. On the other hand, the zirconocene catalysts with indenyl ligand produced the copolymers having exclusively 1,3‐disubstituted cycloheptane units. Furthermore, the copolymer prepared by diphenylmethylene(cyclopentadienyl)(9‐fluorenyl)zirconium dichloride was crosslinked. The diastereostructure of the 1,3‐disubstituted cycloheptane units in the copolymers was not influenced by the stereospecificity of the catalysts used, and a cis ‐structure was preferentially formed. In the case of the copolymerization of ethylene and DD, the C 2V ‐symmetric zirconocene catalysts produced the copolymers with 1‐octenyl branches derived from 1,2‐addition propagation of DD. Other C 2 ‐ and C S ‐symmetric zirconocene catalysts with bulky ligands yielded copolymers with crosslinking structures derived form addition propagation of side‐chain unsaturated bond of 1,2‐added DD units.Zirconocene catalysts used in the present investigation.