Deconstructable and Chemically Recyclable High-Density Polyethylene (HDPE)-Like Materials Based on Si–O Bonds

Polyethylene (PE) is the most widely produced synthetic polymer. By installing chemically cleavable bonds into the backbone of PE, it is possible to produce chemically deconstructable PE derivatives. To date, such designs have primarily relied on carbonyl- and olefin-related functional groups. Bifunctional silyl ethers (BSEs; SiR2(OR’2)) could expand the functional scope of PE mimics as they possess strong Si–O bonds, excellent oxidative stabilities, facile chemical tunability, and they may open new avenues for chemical recycling. Here, we report BSE-containing high-density polyethylene (HDPE)-like materials synthesized through a one-pot catalytic ring-opening metathesis polymerization (ROMP) and hydrogenation sequence. The crystallinity of these materials can be adjusted by varying the BSE loading or the steric bulk of the Si-substituents, providing handles to control thermomechanical properties while maintaining the high thermal stability of HDPE. Two methods for chemical recycling of HDPE mimics are introduced, including a circular approach that leverages acid-catalyzed Si–O bond exchange with 1-propanol. Finally, both high molecular weight virgin and chemically-recycled BSE-based HDPE-like materials display mechanical properties similar to commercial HDPE.