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Synthesis and characterization of elastoplastic poly(styrene‐ co ‐ethylene) using novel mono(η 5 ‐cyclopentadienyl) titanium and modified methylaluminoxane catalysts
Author(s) -
Zhu Fangming,
Fang Yutang,
Lin Shangan
Publication year - 1999
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/(sici)1097-4628(19991114)74:7<1851::aid-app30>3.0.co;2-2
Subject(s) - methylaluminoxane , copolymer , styrene , polymer chemistry , ethylene , materials science , metallocene , polymerization , polystyrene , tacticity , catalysis , titanium , solvent , chemistry , organic chemistry , polymer , composite material , metallurgy
Elastoplastic poly(styrene‐ co ‐ethylene) with high molecular weight was synthesized using novel mono(η 5 ‐pentamethylcyclopentadienyl)tribenzyloxy titanium [Cp*Ti(OBz) 3 ] complex activated with four types of modified methylaluminoxanes (mMAO) containing different amounts of residual trimethylaluminum (TMA). The ideal mMAO, used as a cocatalyst for the copolymerization of styrene with ethylene, contains TMA approaching to 17.8 wt %. The oxidation states of the titanium‐active species in different Cp*Ti(OBz) 3 /mMAO catalytic systems were determined by the redox titration method. The results show that both active species may exist in the current system, where one [Ti(IV)] gives a copolymer of styrene and ethylene, and the second one [Ti(III)] only produces syndiotactic polystyrene (sPS). Catalytic activity, compositions of copolymerization products, styrene incorporation, and copolymer microstructure depend on copolymerization conditions, including polymerization temperature, Al/Ti, molar ratio, and comonomers feed ratio. The copolymerization products were fractionated by successive solvent extractions with boiling butanone and tetrahydrofuran (THF). The copolymer, chiefly existing in THF‐soluble fractions, was confirmed by 13 C‐NMR, GPC, DSC, and WAXD to be an elastoplastic copolymer with a single glass transition temperature. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1851–1857, 1999