Beaver dam-inspired semi-interpenetrating polymer network with local crosslinks: A synergistic approach for high-strength, flame-retardant, and thermally stable thermoplastic composites

To overcome the challenge of simultaneously optimizing multiple properties in thermoplastic resins, we propose a molecular network strategy inspired by the branch-skeleton–clay interlocking architecture of beaver dams. In this bioinspired design, rigid entangled polymer chains form a branch-like skeletal network, while amino- and cyano-based secondary crosslinks act as clay-like fillers. This hierarchical structure mimics the graded energy dissipation mechanism found in natural dams. The optimized polymer exhibits outstanding performance: compressive strength of 200.6 MPa at 25 °C, >85 % modulus retention at 150 °C, and an intrinsic UL-94V-0 flame-retardant rating, with 1 % weight-loss temperatures of 441 °C (N₂) and 435 °C (air). This approach yields a new class of resin matrices combining mechanical robustness, intrinsic flame resistance, and thermal stability for extreme applications (e.g., high-temperature aerospace seals and flame-resistant 5G electronics housings).