Dual Sacrificial Strategy Toward Tough and Recyclable CO₂-Sourced Epoxy Thermosets

Developing thermosetting epoxy resins that concurrently deliver high performance (integrating superior strength with toughness) and chemical recyclability presents a persistent challenge in sustainable polymer advancement. Herein, we present a dual sacrificial strategy employing CO₂-derived poly(ether-carbonate) (PPC) polyols as functional epoxy hardeners. Flexible ether segments serve as sacrificial components enhancing toughness, while cleavable carbonate groups function as sacrificial sites facilitating degradation. This dual sacrificial design in PPC polyols demonstrably enhances mechanical properties while enabling degradability. Model reactions and curing kinetics analyses reveal a distinctive dual-stage crosslinking process governed by hydroxyl transfer mechanisms. The resulting hierarchical cure yields thermosets with unconventional hyperbranched topologies embedded within uniform network structures, conferring: 1) tunable thermomechanical properties (T_g = 53-129 °C) through precise polyol content control; 2) substantially elevated toughness (up to 5.2 MJ m^-3), exceeding conventional epoxy resins by >300%; and 3) rapid catalytic chemical recyclability (<4 h at 60 °C), with degradation products functioning as reusable hardeners. Practical validation via glass fiber-reinforced composites and electronic packaging confirms robust performance with full recyclability. This integrated methodology reconciles the historical trade-off between mechanical robustness and chemical recyclability in thermosets, establishing a viable pathway toward sustainable epoxy production.