Crystallite-Templated Solid-State Synthesis of Blocky Polyethylene Copolymers

Block copolymers of polyethylene (PE) hold great promise for advanced materials applications but remain synthetically challenging due to PE’s inert backbone, poor solubility, and limited tolerance to polar functionalities. Here, we report a modular synthetic platform for accessing varied PE-based materials via blocky copolymers of PE and polycyclooctene (PCOE), denoted PE-blocky-PCOEs. These polymers are synthesized through a streamlined tandem process comprising ring-opening metathesis polymerization (ROMP), followed by solid-state hydrogenation. Selective hydrogenation of the amorphous domains yields saturated PE blocks, while the crystalline domains remain as unsaturated PCOE blocks. Tuning hydrogenation conditions results in PE-blocky-PCOEs with adjustable PE block lengths (Mp = 2660–11800 Da) and internal alkenes amenable to further functionalization. The reactivity of these alkenes is demonstrated via subsequent epoxidation, giving PE-blocky-epoxidized-PE (PE-blocky-ePE) copolymers templated by the original composition. This solid-state hydrogenation strategy provides a versatile route to compositionally complex and functional PE-based block copolymers.