Syntheses of Well-Defined Functional Isotactic Polypropylenes via Efficient Copolymerization of Propylene with ω-Halo-α-alkenes by Post-metallocene Hafnium Catalyst

Abstract

Catalyzed by the (pyridylamido)hafnium/organoboron system, a series of halogen-functionalized isotactic polypropylenes were synthesized via the stereospecific copolymerization of propylene with ω-halo-α-alkenes. The (pyridylamido)hafnium/organoboron system has been proved to be a potent catalyst for propylene/ω-iodo-α-alkenes copolymerization, producing well-defined poly(propylene-co-ω-iodo-α-undecene)s with outstanding properties. The high molecular weight (Mw > 100 kg mol–1) functional iPPs possessing abundant iodoalkene units (up to 11.7 mol %) and unimodal molecular weight distributions (Mw/Mn ≈ 2) could be easily obtained under mild conditions with excellent catalytic activity. High isotactic selectivity of monomers, including propylene and polar comonomer, was unexpectedly observed ([mmmm] > 99%). Moreover, based on the unique copolymerization process and the highly reactive sites on the copolymers, the halogen groups of the resultant copolymers could be easily transformed into other polar groups via click chemistry, and the new functional iPPs with high molecular weights and abundant polar groups could be efficiently obtained.