Upcycling of thermosetting polymers into high-value materials

Abstract

Thermosetting polymers, a large class of polymers featured with excellent properties, have been widely used and played an irreplaceable role in our life. Nevertheless, they are arduous to be recycled...

High-Performance Recyclable and Malleable Epoxy Resin with Vanillin-Based Hyperbranched Epoxy Resin Containing Dual Dynamic Bonds

“…Epoxy resins are widely applied in adhesives, coatings, electronic packaging materials, and composites due to their excellent mechanical properties, heat resistance, chemical resistance, and dimensional stability. − However, the covalent cross-linking structure hampers the recycling of epoxy-based products. , It is of great importance to develop technologies for recycling epoxy resins at the end of use. − …”

Closed-Loop Recycling of Polyols from Thermoset Polyurethanes by tert-Amyl Alcohol-Mediated Depolymerization of Flexible Foams

“…For thermoplastic materials, the chemical morphology offers recycling possibilities through mechanical, gasification, pyrolysis, solvolysis, or hydrogenolysis processes. − While these processes provide plastic waste with a second life cycle, several recycling technologies suffer from high cost, production of secondary pollutants, and downgrading of the plastic materials into a secondary feed, limiting the practical application. Although these materials are not part of a closed-loop recycling process, there is a high demand for products stemming from the mechanical and chemical recycling of thermoplastics. , As opposed to thermoplastics, the absence of good recycling methods for thermoset plastics results in end-of-life materials being sent to landfilling, used as fillers, or simply incinerated for heat or fiber recovery. − The lack of good recycling methods is a direct result of the chemical morphology of thermoset plastics, displaying covalent intermolecular cross-linkages, which create strength and stiffness reducing the susceptibility to damage . With increasingly strict environmental legislation and resource depletion, our society needs to establish either value-chains around new thermoset polymers, which are recyclable by design, such as polymers with dynamic covalent bonds that deconstruct upon external stimuli, and/or new ways to recycle commodity polymers for reuse .…”

Closed-Loop Recyclable Vinylogous Carbamothioate-Based Covalent Adaptable Networks

“…due to their high mechanical properties and chemical and heat resistance . However, intrinsic permanently cross-linked network structure limits the potential for reprocessing and recycling of thermosets, resulting in environmental pollution and waste of fossil energy. − To achieve a circular polymer economy, closed-loop chemical recycling of polymers under ambient conditions becomes an ingenious method that allows the individual recovery of monomeric species from the original network, thus enabling the reuse of the separated monomers to reform new network polymers or produce new materials. − …”