Interface Design in Bioinspired Polymer Composites: Mechanisms, Characterization, Processing, and Multiscale Modeling

Natural biological materials with a few polymers have demonstrated that intricate interfaces on a hierarchical scale are important to efficient load transfer, crack deflection, and energy dissipation. Inspired by them, bioinspired polymer composites have been developed for enhanced strength and toughness. However, a few review papers systematically summarize the interface progress in bioinspired polymer composites. This progress provides a systematic and critical overview of interface strategies and strengthening mechanisms in bioinspired polymer composites. We first review the fundamental mechanical roles of interfaces, including stress transfer, polymer chain mobility, interfacial energy dissipation, and crack propagation mechanisms. Particular emphasis is placed on chemical interfaces—such as hydrogen bonding, ionic coordination, and covalent coupling—as well as interlocking interfaces inspired by mineral bridges, nanoasperities, and suture‐like geometries. Advanced experimental techniques for characterizing interfacial properties are reviewed, including atomic force microscopy and micromechanical testing. Furthermore, we discuss recent progress in numerical simulations and machine learning approaches, which together enable multiscale understanding and rational design of interfaces. Finally, we distill current challenges and future perspectives in the interface, highlighting the demand for an integrated experimental–computational approach to design bioinspired polymer composites with exceptional mechanical performance.