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@article{561446,
author = {Skeřil, Robert and Salajka, Zdeněk and Šindelář, Pavel and Mach, Karel and Horáček, Michal and Varga, Vojtěch and Císařová, Ivana and Pinkas, Jiří},
article_number = {224},
keywords = {Titanium; Constrained geometry catalysts; Copolymerization ethenestyrene; Copolymers ethenestyrene; Crystal structures},
language = {eng},
issn = {1381-1169},
journal = {Journal of molecular catalysis A:Chemical},
title = {Copolymerization of ethene with styrene using CGC catalysts: the effect cyclopentadienyl ligand substitution on the catalyst activity and the copolymer structure},
volume = {2004},
year = {2004}
}
TY - JOUR
ID - 561446
AU - Skeřil, Robert - Salajka, Zdeněk - Šindelář, Pavel - Mach, Karel - Horáček, Michal - Varga, Vojtěch - Císařová, Ivana - Pinkas, Jiří
PY - 2004
TI - Copolymerization of ethene with styrene using CGC catalysts: the effect cyclopentadienyl ligand substitution on the catalyst activity and the copolymer structure
JF - Journal of molecular catalysis A:Chemical
VL - 2004
IS - 224
SP - 97-103
EP - 97-103
PB - ELSEVIER
SN - 13811169
KW - Titanium
KW - Constrained geometry catalysts
KW - Copolymerization ethenestyrene
KW - Copolymers ethenestyrene
KW - Crystal structures
N2 - The ethenestyrene copolymerization has been investigated using the dimethylsilylene-bridged (amidocyclopentadienyl)dichlorotitanium( IV) complexes [TiCl2{5-1-(SiMe2Nt-Bu-N)-2,3,4-Me3-5-R-C5}], where R=Me (1), H (2), Bu (3), Ph (4), 4-fluorophenyl (5), and but-2-en-2-yl (6) in combination with methylalumoxane (MAO) as catalysts. The nature of the substituent R strongly influenced the catalyst activity and selectivity and the copolymer microstructure and molecular weight. The catalysts derived from 1 to 3 were by about one order more active than those derived from 4 to 6. At the optimum Al/Ti molar ratio of 900, the highly active catalysts produced a pseudo-random copolymer (9597 wt.%) containing up to 47.8 mol% of incorporated styrene. The low-active catalysts gave mixtures of a pseudo-random copolymer (7685 wt.%) with polyethene (10 wt.%) and polystyrene sequences (37 wt.%). The X-ray diffraction crystal structures of 2 and 4 were determined. Comparison of crystal structures of 1 and 2 versus 4 and 5 revealed a slightly shorter distances TiCg (Cg centroid of the cyclopentadienyl ring) and slightly larger ClTiCl angles in 1 and 2, indicating a higher electron density at the titanium atom. An electron attracting effect of phenyl or alkenyl substituents as well as their steric hindrance can account for a low catalytic performance of 46/MAO catalysts.
ER -
SKEŘIL, Robert, Zdeněk SALAJKA, Pavel ŠINDELÁŘ, Karel MACH, Michal HORÁČEK, Vojtěch VARGA, Ivana CÍSAŘOVÁ and Jiří PINKAS. Copolymerization of ethene with styrene using CGC catalysts: the effect cyclopentadienyl ligand substitution on the catalyst activity and the copolymer structure. \textit{Journal of molecular catalysis A:Chemical}. ELSEVIER, 2004, vol.~2004, No~224, p.~97-103. ISSN~1381-1169.
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