Factors affecting product distributions in ethylene/styrene copolymerization by (aryloxo)(cyclopentadienyl)titanium complexes‐MAO catalyst systems |
| |
Authors: | Kotohiro Nomura Hao Zhang Doo‐Jin Byun |
| |
Affiliation: | Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST), 8916‐5 Takayama, Ikoma, Nara 630‐0101, Japan |
| |
Abstract: | Ethylene/styrene copolymerizations using Cp′TiCl2(O‐2,6‐iPr2C6H3) [Cp′ = Cp* (C5Me5, 1 ), 1,2,4‐Me3C5H2 ( 2 ), tert‐BuC5H4 ( 3 )]‐MAO catalyst systems were explored under various conditions. Complexes 2 and 3 exhibited both high catalytic activities (activity: 504–6810 kg‐polymer/mol‐Ti h) and efficient styrene incorporations at 25, 40°C (ethylene 6 atm), affording relatively high molecular weight poly (ethylene‐co‐styrene)s with unimodal molecular weight distributions as well as with uniform styrene distributions (Mw = 6.12–13.6 × 104, Mw/Mn = 1.50–1.71, styrene 31.7–51.9 mol %). By‐productions of syndiotactic polystyrene (SPS) were observed, when the copolymerizations by 1 – 3 ‐MAO catalyst systems were performed at 55, 70 °C (ethylene 6 atm, SPS 9.0–68.9 wt %); the ratios of the copolymer/SPS were affected by the polymerization temperature, the [styrene]/[ethylene] feed molar ratios in the reaction mixture, and by both the cyclopentadienyl fragment (Cp′) and anionic ancillary donor ligand (L) in Cp′TiCl2(L) (L = Cl, O‐2,6‐iPr2C6H3 or N=CtBu2) employed. Co‐presence of the catalytically‐active species for both the copolymerization and the homopolymerization was thus suggested even in the presence of ethylene; the ratios were influenced by various factors (catalyst precursors, temperature, styrene/ethylene feed molar ratio, etc.). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4162–4174, 2008 |
| |
Keywords: | copolymerization ethylene styrene/half‐titanocene titanium |
|
|