Complementary Hydrogen-Bonded Dual-Network Bismaleimides for Cohesive Adhesion at Metal–Polymer Interfaces

Herein, we present a strategy for designing thermally stable adhesive compositions that synergistically balance hydrogen-bond-mediated interfacial adhesion with network-derived bulk cohesion. Complementary hydrogen bonding between carbazole- and benzophenone-based bismaleimides (BMIs) establishes a cohesive molecular framework, while 2,2′-diallylbisphenol A (DABPA)-mediated allyl–maleimide ene reactions regulate network evolution to alleviate brittleness and improve processability. Subsequent incorporation of low-viscosity epoxy prepolymer promotes substrate wetting and generates hydroxyl functionalities during curing while yielding an interpenetrating polymer network. Nonisothermal differential scanning calorimetry analyses of the BMI compositions revealed pseudo-first-order curing behavior, and kinetic modeling demonstrated composition-dependent curing kinetics that govern curing reactivity and melt processability. With the subsequent incorporation of 30 phr of epoxy prepolymer, BMI–DABPA exhibited a low melt viscosity of 0.019 Pa·s, providing sufficient fluidity for resin spreading and substrate wetting. The resulting complementary hydrogen-bonded dual-network BMI adhesive delivered a lap shear strength of 11.53 MPa on an Fe substrate while maintaining excellent thermal stability (Td5% > 407 °C; char yield >43% at 800 °C). This work demonstrates the potential of balancing adhesion, cohesion, and processing characteristics in BMI adhesives by designing a reactive monomer system of sufficiently low viscosity, providing a rational molecular design strategy for future developments.