Dynamic Covalent Strategies for Balancing Reprocessability and Service Stability in Recyclable Thermoset-Like Polymer Networks | RISE Research

This review paper examines how dynamic covalent chemistry can make thermoset-like polymer networks more recyclable while still preserving enough service stability for real applications. Rather than organizing strategies by chemistry type alone, the paper organizes them by likely application: high-performance structural composites, reprocessable engineering parts, repairable coatings and adhesives, and lower-to-medium-load materials that reuse thermoset waste. Five main strategies are compared: imine-containing epoxies and hyperbranched supramolecular thermosets, which preserve strong thermoset-like mechanical performance (comparable tensile strength to commercial epoxies) while enabling fiber recovery or rapid closed-loop recycling, making them best suited for high-value carbon-fiber composites and specialty parts; disulfide-based epoxy vitrimers and catalyst-free transesterification vitrimers, which allow repeated reshaping and repair (one system withstood 10 reprocessing cycles without property loss) and fit reprocessable engineering parts, coatings, and adhesives; and reversible Diels-Alder epoxy blends, which are thermally reversible but mechanically weaker, making them a practical route for downcycling and reusing lower-value thermoset waste rather than structural use. The review argues there is no single best recyclable thermoset strategy, since each chemistry solves a different version of the reprocessability-versus-stability tradeoff, and the right choice depends on the required balance of reprocessing conditions, mechanical strength, thermal and environmental durability, and cost. The discussion section raises practical concerns often overlooked in individual studies, including synthesis cost, the true industrial cost of reprocessing steps, environmental risks from fluorinated activating groups or unrecovered solvents, and scale-up challenges with mixed real-world waste streams. The paper concludes that future research should prioritize demonstrating long-term durability, repeated recycling performance, and full life-cycle sustainability rather than one-time proof of recyclability.