Thermally Robust yet Deconstructable and Chemically Recyclable High‐Density Polyethylene (HDPE)‐Like Materials Based on Si−O Bonds

• Published in: Angewandte Chemie International Edition Vol. 62; no. 51; pp. e202315085 - n/a
• Main Authors: Johnson, Alayna M., Johnson, Jeremiah A.
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 18.12.2023
• Edition: International ed. in English
• Subjects: Bonding strength; Carbonyl compounds; Carbonyls; Chemical bonds; Chemical recycling; Chemical synthesis; Closed Loop Recycling; Ethers; Functional groups; Green Chemistry; High density polyethylenes; Mechanical properties; Metathesis; Molecular weight; Polyethylene; Polyethylene Mimic; Polymerization; Polymers; Propanol; Recycling; Ring-Opening Polymerization; Silyl Ether; Thermomechanical properties; Green Chemistry; Ring-Opening Polymerization; Closed Loop Recycling; Polyethylene Mimic; Silyl Ether
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202315085

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, however, 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 and facile chemical tunability. 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 concentration or the steric bulk of the Si‐substituents, providing handles to control thermomechanical properties. 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. Additionally, despite the fact that the starting HDPE mimics were synthesized by chain‐growth polymerization (ROMP), we show that it is possible to recover the molar mass and dispersity of recycled HDPE products using step‐growth Si−O bond formation or exchange, generating high molecular weight recycled HDPE products with mechanical properties similar to commercial HDPE. Bifunctional silyl ether (BSE)‐containing high‐density polyethylene (HDPE)‐like materials have been synthesized under mild polymerization and hydrogenation conditions. Both the concentration of BSEs in the polymer chain and the silicon steric bulk can be tuned to yield materials with HDPE‐like thermomechanical properties. The materials undergo two distinct deconstruction pathways and can be recycled without compromising their mechanical strength.