Dual Dynamic Chemistries Enable Tough and Degradable Bio-Based Vitrimers

The pursuit of high-performance thermosets and carbon fiber reinforced polymers (CFRPs) with enhanced sustainability is hampered by a tradeoff: performance or recyclability. Here we explore a novel bio-based formulation utilizing disulfide and silyl ether chemistries (DVSS₅₀SiO₅₀) alongside the mono-dynamic resins. Carbon fiber recovery is shown in the case of the dual-dynamic resin (some residue) and the pure silyl ether resin (complete) under chemoselective recycling conditions, confirming the potential for Si─O bonds to enable facile degradability. Incorporation of disulfide linkages via an aniline-based aryl disulfide monomer enhances stress relaxation, unlocking faster reformability without sacrificing structural integrity. Mechanical reprocessing of the resins yielded materials with similar stiffness but a slight decrease in the T_g of the resins. High K_Q fracture toughness values were observed, driven by the vanillyl alcohol-derived epoxy monomer and proposed mechanochemical activation of dynamic bonds at the crack tip. This initial investigation shows that a combination of dynamic and selectively cleavable chemistries could enable high-performance thermosets with reformability, mechanical recyclability, and mild chemical degradation for fiber recovery. Additionally, the tradeoff between enhanced chemical degradability and stress relaxation arising from Si─O and S─S bonds is shown.