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Heterogeneous ethylene polymerization catalysts were prepared by supporting tetrakis(dimethylamino)titanium, Ti[N(CH 3 ) 2 ] 4 , on chemically modified silica surface. The modification of silica was made using a silane coupling agent, Cp(CH 2 ) 3 Si(OCH 2 CH 3 ) 3 and atomic layer chemical vapor deposition (ALCVD). Titanium amide was also immobilized straight on the silica and on a methyllithium-treated modified silica. The aim of methyllithium treatment was to alkylate the unreacted ethoxy groups of the silane coupling agent on the silica. Methyllithium methylates, besides ethoxy groups, also silica surface and surface cyclopentadienyl groups. A model compound for these heterogeneous catalysts was prepared using a reaction of Ti[N(CH 3 ) 2 ] 4 with trimethylsilylcyclopentadienyl yielding a monocyclopentadienyl titanium compound, Me 3 SiCpTi[N(CH 3 ) 2 ] 3 . The preliminary results of ethylene polymerization using the prepared heterogeneous and homogeneous titanocene amide complexes and the effect of amount of MAO are presented. |
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