Direct Synthesis of Ultrahigh Molecular Weight Functionalized Isotactic Polypropylene

Ultrahigh molecular weight functionalized isotactic polypropylene (f-UHMW-iPP) through the direct copolymerization of propylene with polar monomers is highly desirable but has not been accessed thus far because it involves challenging regio-and stereo chemistry along with usually reduced molecular weight. Herein, in contrast to the unsuccessful catalyst strategy, a polar monomer-assisted strategy is used to access the above material. The introduction of O- or S-functionalized long-chain polar olefins into the hafnium-catalyzed copolymerization of propylene (and bulkier alpha-olefins) significantly increases the copolymer molecular weight with a maximum observed increase of +488%. f-UHMW-iPP and functionalized isotactic poly(alpha-olefin)s (Mw > 2000 kDa, [mmmm]: 99%) are thus prepared at ambient conditions. The incorporation of 1 mol % of polar monomer improves the surface property and significantly increases the long-sought toughness (860%) of brittle iPP, without reducing the tensile strength (42 MPa) due to the key achievement of ultrahigh molecular weight. A discussion of the mechanism involved in the beneficial effects of incorporating the polar monomer is herein presented by an in-depth density functional theory calculation.