Zirconocene-MAO catalyzed homo- and copolymerizations of linear asymmetrically substituted dienes with propene: a novel strategy to functional (co)poly(α-olefin)s

Abstract

The polymerization behavior of three linear asymmetrically substituted dienes, i.e. 6-phenyl-1,5-hexadiene (A), 7-methyl-1,6-octadiene (B) and R(+)-5,7-dimethyl-1,6-octadiene (isocitronellene, C) is reported in order to study the effect of substitution at one vinylic group. Homopolymerization of these monomers with the catalyst system rac-Et[Ind]2ZrCl2/MAO resulted in no reaction products in the case of monomer A and in polymers with Mw = 3.5 kg/mol and Mw = 14.0 kg/mol with the monomers B and C, respectively. According to NMR analysis, the vinylene end group of isocitronellene remained untouched during polymerization, which excludes the possibility of cyclopolymerization or crosslinking. Copolymerization of isocitronellene with propene resulted in incorporation of the diene (15.6 mol-%) equal to the stoichiometric ratio in the monomer feed, with a relatively high catalyst activity. The degree of incorporated isocitronellene is inversely related to the polymerization temperature, providing control over crystallinity (isotacticity) and molecular weight of the copolymer. The isocitronellene homo- and copolymers could be epoxidized quantitatively and brominated to an extent of 90%. Perfluorohexyl iodide was grafted onto the isocitronellene/propene copolymer by radical reaction (conversion 80%), yielding a poly(α-olefin) with fluorinated side chains.