Copolymerization of propylene with various higher alpha-olefins using silica-supported rac-Me2Si(Ind)(2)ZrCl2

The copolymerization of propylene with 1-hexene, 1-octene, 1-decene, and 1- dodecene was carried out with silica-supported rac-Me2Si(Ind)(2)ZrCl2 as a catalyst. The copolymerization activities of the homogeneous and supported catalysts and the microstructures of the resulting copolymers were compared . The activity of the supported catalyst was only one-half to one-eighth of that of the homogeneous catalyst, depending on the comonomer type. The sup ported catalyst copolymerized more comonomer into the polymer chain than th e homogeneous catalyst at the same monomer feed ratio. Data of reactivity r atios showed that the depression in the activity of propylene instead of an enhancement in the activity of olefinic comonomer was responsible for this phenomenon. We also found that copolymerization with alpha -olefins and su pporting the metallocene on a carrier improved the stereoregularity and reg ioregularity of the copolymers. The melting temperature of all the copolyme rs decreased linearly with growing comonomer content, regardless of the com onomer type and catalyst system. Low mobility of the propagation chain in t he supported catalyst was suggested as the reason for the different polymer ization behaviors of the supported catalyst with the homogeneous system. (C ) 2001 John Wiley & Sons, Inc.