Facile functionalization of isotactic polypropylene via click chemistry

We report here a new strategy for facile functionalization of isotactic polypropylene (iPP) via click chemistry. iPP bearing trimethylsilyl (TMS) protected alkynyl groups was prepared through copolymerization of propylene with a small amount of functional α-olefins with a zirconocene complex/AliBu3/[Ph3C][B(C6F5)4] catalytic system. The obtained copolymers exhibited high molecular weights beyond 2.0 × 105 and unimodal molecular distributions, with comonomer incorporation in the range of 1 to 4 mol% while maintaining good isotacticity ([mmmm] > 94%). Functionalization of the copolymers was achieved via TMS deprotection and click reactions in one-pot, providing a facile and efficient route to scalable fabrication of iPPs with diverse functionalities and improved physical properties. For instance, polyethylene glycol (PEG) was successfully grafted onto iPP polymer chains with a weight percentage up to 71.1%. Consequently, the hydrophilicity of the resultant copolymer was remarkably enhanced as revealed by the three times larger swelling of PEG-functionalized iPP after soaking in water for only a few minutes.