Bio-Inspired Rigid-Flexible Integrated Materials With Gradient Interphases for Superior Energy Dissipation

Bio-inspired rigid-flexible integrated architectures effectively mitigate the intrinsic trade-off between strength and toughness. However, conventional rigid-flexible architectures assembled by adhesives or non-covalent interactions typically suffer from weak interfacial bonding and modulus-mismatch-induced stress concentration, thereby causing delamination. Here, we report a facile strategy combining monomer diffusion with network reconfiguration to construct rigid-flexible multilayered materials with continuous modulus gradient interphases. The optimized 7-layer gradient material (7L-G), comprising rigid polydicyclopentadiene and its flexible copolymers, exhibits a high tensile strength of 51.7 MPa and an elongation at break of 261.0%. Real-time fluorescence tracking using aggregation-induced emission molecules and quantum dots reveals the monomer diffusion kinetics, while nanoindentation confirms a ∼60 µm-thick gradient transition interphase. Both quasi-static tensile and split Hopkinson tension bar (SHTB) tests demonstrate that the 7L-G sample displays significantly superior energy dissipation to its non-gradient counterparts. This enhancement is attributed to the efficient stress delocalization and coordinated plastic deformation enabled by the gradient interphases. Ballistic impact tests and numerical simulations demonstrate the exceptional ballistic resistance performance of the 7L-G sample. This study confirms the effectiveness of modulus gradient interphases in enhancing the interfacial integrity and energy dissipation of rigid-flexible materials, and provides a versatile strategy for developing high-performance impact-resistant polymer materials.