Constructing High‐ T g and Ultra‐Strong Multifunctional Thermosets Enabled by Acid‐Base Ion Pairs

ABSTRACT Thermosetting epoxy resins (TERs) play pivotal roles in aerospace, wind energy, and electronic packaging. However, due to the inherent constraints of these properties in molecular design, previously reported TERs have always faced a “seesaw” dilemma, enhancing glass transition temperature ( T g ) and mechanical strength typically compromises elasticity and reprocessability. Herein, an innovative molecular engineering strategy is proposed to integrate high‐energy‐dissipation acid‐base ion pairs (ABIPs) into densely crosslinked covalent adaptable networks, constructing high T g and ultra‐strong TERs (named SEP ‐COOH ). It demonstrated two breakthrough advantages: First, SEP ‐COOH exhibits an exceptional combination of high T g (> 245°C), excellent mechanical strength (77.9 ± 1.5 MPa), and impact toughness (8.2 MJ m −2 ), and its outstanding performance is comparable to that of low‐viscosity resins (Hexion and Toray RS‐50) for structural applications. Second, the internal catalytic effect of ABIPs on ester exchange is unprecedented, which not only integrates the internal catalysis of tertiary amines and the effect of neighboring groups but also achieves a breakthrough. This built‐in catalysis allows ultrafast surface reprocessing to achieve superhydrophobicity and improve the thermal conductivity of its composites. The integration of toughness, thermal stability, and reprocessability represents a breakthrough in epoxy thermoset design, offering a sustainable pathway for recyclable high‐performance polymers.