Copolymerization of propylene and 1,5-hexadiene with stereospecific metallocene/Al(i-Bu)3/[Ph3C][B(C6F5)4

Abstract

Copolymerizations of propylene (P) with 1,5-hexadiene (1,5-HD) were carried out with isospecific rac-1,2-ethylenebis(1-indenyl)Zr(NMe2)2 [rac-(EBI)Zr(NMe2)2, 1] and syndiospecific isopropylidene(cyclopentadienyl)(9-fluorenyl)ZrMe2 [i-Pr(Cp)(Flu)ZrMe2, 2] compounds combined with Al(i-Bu)3/[Ph3C][B(C6F5)4] as a cocatalyst system. Microstructures of poly(propylene-co-1,5-HD) were determined by 1H NMR, 13C NMR, Raman spectroscopies and X-ray powder diffraction. The isospecific 1/Al(i-Bu)3/[Ph3C][B(C6F6)4] catalyst showed much higher polymerization rate than 2/Al(i-Bu)3/[Ph3C][B(C6F6)4] system, however, the latter system showed higher incorporation of 1,5-HD (rP = 8.85, r1,5-HD = 0.274) than the former system (rP = 16.25, r1,5-HD = 0.34). The high value of rP × r1,5-HD far above 1 demonstrated that the copolymers obtained by both catalysts are somewhat blocky. The insertion of 1,5-HD proceeded by enantiomorphic site control; however, the diastereoselectivity of the intramolecular cyclization reaction of 1,2-inserted 1,5-HD was independent of the stereospecificity of metallocene compounds, but dependent on the concentration of 1,5-HD in the feed. The insertion of the monomers by enantiomorphic site control could also be realized by Raman spectroscopy and X-ray powder diffraction of the polymers. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1590–1598, 2000