Copolymerization of propylene with higher α-olefins in the presence of the syndiospecific catalysti-Pr(Cp)(9-Flu)ZrCl2/MAO

Abstract

The catalyst system i-Pr(Cp)(9-Flu)ZrCl2/methylaluminoxane was used for the synthesis of random syndiotactic copolymers of propylene with 1-hexene, 1-dodecene, and 1-octadecene as comonomers. An investigation of the microstructure by 13C NMR spectroscopy revealed that the stereoregularity of the copolymers decreased because of an increase in skipped insertions in the presence of the higher 1-olefin. The melting temperature of the copolymers, as measured by differential scanning calorimetry (DSC), decreased linearly with increasing comonomer content independently of the comonomer nature. During the DSC heating cycle, an exothermic peak indicating a crystallization process was observed. The decrease in the crystallization temperature with higher 1-olefin content, measured by crystallization analysis fractionation, indicated a small but significant dependence on the nature of the comonomer. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 128–140, 2002