Synthesis and properties of polyethylene and polypropylene containing hydroxylated cyclic units in the main chain

Polyethylene and isotactic polypropylene containing hydroxylated cyclic units were synthesized by copolymerization of ethylene or propylene and cyclodiolefins, dicyclopentadiene (DCPD), 5-vinyl-2-norbornene (VNB), 5-ethylidene-2-norbornene (ENB), with zirconocene catalysts and subsequent hydroboration reaction of residual unsaturated group. The resulting hydroxylated copolymers showed higher glass transition temperature (Tg) than the original and hydrogenated copolymers. Relationship between the cyclodiolefin content and ΔTg (ΔTg=difference of Tg between hydroxylated copolymer and hydrogenated copolymer) was given by a straight line independent of the structure of the comonomers. Improvement in shape memory effect was observed in the hydroxylated ethylene-VNB copolymer.