Linear or branched polyethylenes from supported aryloxytitanium(IV)-cyclopentadienyl complexes

ABSTRACT: The reaction of titanium-piano stool complexes (1-4) with poly(styrene-r-4-hydroxystyrene) afforded immobilized aryloxycyclopentadienyl complexes ((5-8), macroligated catalyst). These macroligated catalysts have low solubility in toluene, indicative of chemical cross-linking. The formation of chemical cross-links is attributed to the titanium being ligated with two aryloxy units. Elemental analysis and 13C NMR have confirmed the presence of the mono- and bis(aryloxy) components in these macroligated catalysts. In conjunction with MAO as the cocatalysts, the macroligated catalysts have been used for ethylene homopolymerization. The resulting polymers were either linear polyethylene or polyethylene having exclusively butyl short chain branches (SCBs). The formation of SCBs was found to be dependent on the cyclopentadienyl substituents, the influence exerted by the polymeric macroligand, and the nature of the cocatalysts. The thermal transitions and apparent crystal sizes as determined by wide-angle X-ray diffraction and 13C NMR are consistent with polyethylene having butyl short chain branches evenly distributed along the polymer backbone