ISOTACTIC POLYPROPENE PREPARED USING MgCl_2 SUPPORTED ZIEGLER-NATTA CATALYSTS CONTAINING NOVEL DIETHER DONORS

摘要

In recent years, the MgCl_2-supported catalysts containing diethers as internal donors shown very high activity, isotaticity and sensitivity toward hydrogen, thus making them to be competitive with heterogeneous catalysts, which are commercially used at present. Due to the stability of diethers toward AlEt_3, they can not be extracted from the catalysts and the external donors are not needed in the polymerization. From a scientific point of view, the diether-based catalysts simplified the polymerization system and made it possible to understand the mechanisms of polymerization and the function of the donors. Some results reported have previously shown that the bulkiness of 2-substituents plays an important role in improving the catalyst activity and stereospecificity. In this paper, novel catalysts with internal donors 9,9-bis(methoxymethyl) fluorene (BMF) and 3-methoxymethyl dibenzofuran (MBF) for propene polymerization without external donors are reported. The structures of diethers BMP and MBF are shown in Fig.1. The effect of polymerization conditions on the catalytic activity, as well as isotacticity, molecular weight and melting point of polypropene is investigated.