Toward versatile biobased epoxy vitrimers by introducing aromatic N-heterocycles with stiff and flexible segments

Recyclable materials with simultaneous multifunctionality and high performance, especially polymers synthesized from biobased monomers, have recently attracted a great deal of interest. However, current traditional vitrimers exhibit trade-offs between high performance and reprocessing. To circumvent this inherent contradiction, we report the first attempt to introduce an aromatic N-heterocycles (the fixed ‘stiff’ segments) derived from biomass functionalized with ester groups (the dynamic ‘flexible’ segments) into a thermoset system. The resulting resins exhibited high flexural strength (151 MPa) and toughnesses, a high glass transition temperature (205 ℃), intrinsic flame retardancy (UL-94 V-0) and acid/base resistance. In addition, the ester groups and aromatic N-heterocycles enabled dissolution of the network in ethylene glycol without additional catalyst. Importantly, the degradation solution could be directly reused into high-value photothermal conversion coatings and adhesives with 100% recyclability just by evaporating the ethylene glycol at elevated temperatures. Additionally, the conjugated aromatic N-heterocycles enhanced the adhesive properties and photothermal conversion of the system. The ease with which biobased materials bearing N-heterocycles and ester groups can be synthesized, recycled, and reused without losing value provides a new direction for closed-loop, high-performance and versatile polymer life cycles.