Copolymerization of propene and higher alpha-olefins with the metallocene catalyst Et[Ind]2HfCl2/methylaluminoxane

Copolymerizations of propene with higher alpha-olefins including 1-butene, 1-hexene, 1-octene, 1-dodecene and 1-hexadecene were carried out with an isospecific metallocene catalyst (Et[Ind]2HfCl2/methylaluminoxane) at 30 degrees C in toluene. C-13 NMR analysis showed that all products obtained are random copolymers (r(1) . r(2) approximate to 1). The reactivity of the higher cc-olefins in the copolymerization is surprisingly high and decreases only slightly with increasing length of the olefin. The incorporation rates of the comonomers in this study were found to be much higher than those obtained by the use of heterogeneous Ziegler-Natta catalysts. Hence, copolymers with every desired composition and alpha-olefin homopolymers can be prepared. The molecular weight of the copolymers is reduced with rising comonomer content. Melting points and glass transition temperatures studied by means of differential scanning calorimetry show a decrease with rising comonomer content and increasing length of the alpha-olefin.