The Synthesis Of Non-Metallocene Single-Site Catalysts And Their Application In Olefin Polymerization

The aim of this thesis is in search of the catalysts which are moderate and stable for preparing mono-dispersed macroporous materials, by means of syndiotactic polymerization of styrene. So three kinds of non-metallocene catalysts were devised and synthesized, including β-diketonate titanium complexes, titanium-2-hydroxy-benzophenone complex, and dinuclear β-diketonate titanium catalysts. The catalysts such as (bfa)TiC!3, (bfa)2TiCl2, (hmbp)2TiCl2, {[xyl(acac)2]TiC!2}2 and [xyl(acac)2](TiCl3)2 have not been reported in the literatures on syndiotactic polymerization of styrene and substituted styrene up to now. The copolymerizations of P-methylstyrene and styrene, styrene and ethylene were also investigated using some of these catalytic systems.The three kinds of catalysts showed their own polymerization principles. The changes of polymerization activity and polymer properties depended on the structure of complexes, different polymerization conditions such as the catalyst concentration, the molar ratio of Al to Ti, the polymerization temperature and reaction time. The catalytic activity of (hmbp)2TiCl2was lower than β-diketonate titanium catalysts. The catalytic activity of dinuclear β-diketonate titanium catalysts was comparative to mononuclear ones. However, the dinuclear β-diketonate titanium catalyst showed the synergism effect, for example, the lower catalyst concentration and the molar ratio of Al to Ti, the activity reached the maximum value at 80 ℃, the melting temperature of polymer was enhanced. Furthermore, dinuclear β-diketonate titanium complex is also single-site catalyst.The glass transition temperature(Tg) of syndiotactic polystyrene(sPS) was about 98℃. The melting temperature (Tm) of sPS was above 265℃. The molecular weight of sPS was in the range of 9X 104g/mol to 50X 104g/mol, and the molecular weight distribution was from 2.3 to 4.9. TheTg of syndiotactic poly(p-methylstyrene)(sPPMS) was above 100℃. And there occured multi-crystalline forms. The molecular weight of sPPMS was in the range of 4X 104g/mol to 10 X 104g/mol, and the molecular weight distribution was from 1.6 to 6.0. The copolymer of P-methylstyrene and styrene was random copolymer, and also syndiotactic polymer.The (dbm)2Ti(OPh)2 /MgCl2 catalytic system was employed in copolymerization of ethylene and styrene.