Segmented multiblock polyolefin compatibilizers from non-living metathesis chain-shuffling

The mechanical properties of mixed plastics can be enhanced by block copolymer compatibilizer additives. Here we report a series of semi-crystalline/semi-crystalline linear multiblock copolymers of LLDPE and PP, the two most abundant plastics, from a non-living shuffling polymerization. Containing up to 13 individual blocks of PE and PP randomly arranged, the multiblock connectivity, crystallinity, and morphology are characterized with a combination of NMR, DSC, X-ray scattering, microscopy, and theoretical models. We show these semi-crystalline products compatibilize and toughen blends of the two most abundant plastics with an enhancement of tensile modulus. Due to the highly segmented nature of the multiblock copolymers, the crystalline morphology exhibits minimal phase separation and imbibes the amorphous chains in commercial polymer interfaces into the semi-crystalline block copolymer phase by transmission electron microscopy. The work provides access to compatibilizer designs that implement a combination of tie-chain, trapped entanglement, and co-crystallization reinforcement mechanisms for toughening post-consumer blends.