Copolymerization of propylene with 1,3-butadiene using isospecific zirconocene catalysts

Poly(propylene-ran-1,3-butadiene) was synthesized using isospecific zirconocene catalysts and converted to telechelic isotactic polypropylene by metathesis degradation with ethylene. The copolymers obtained with isospecific C2-symmetric zirconocene catalysts activated with modified methylaluminoxane (MMAO) had 1,4-inserted butadiene units (1,4-BD) and 1,2-inserted units (1,2-BD) in the isotactic polypropylene chain. The selectivity of butadiene towards 1,4-BD incorporation was high up to 95% using rac-dimethylsilylbis(1-indenyl)zirconium dichloride (Cat-A)/MMAO. The molar ratio of propylene to butadiene in the feed regulated the number-average molecular weight (Mn) and the butadiene contents of the polymer produced. Metathesis degradations of the copolymer with ethylene were conducted with a WCI6/SnMe4/propyl acetate catalyst system. The 1H NMR spectra before and after the degradation indicated that the polymers degraded by ethylene had vinyl groups at both chain ends in high selectivity. The analysis of the chain scission products clarified the chain end structures of the poly(propylene-ran-1,3-butadiene). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5731–5740, 2007