Topological Structuring of Adhesive Layers to Enhance Resistance Against Interfacial Fracture

The reliable bonding of dissimilar materials is crucial for lightweighting and energy-saving. However, their interface is often susceptible to fracture, impeding the widespread adoption of composites. While tough adhesion relying only on intermolecular interactions has been effective for specific adherends, fracture strength is significantly impaired depending on the adhesive selection. Here we introduce an alternative approach that combines chemical affinity with structural interlocking. Our method involves creating a porous layer strongly interacting with one adherend. This porous architecture templates a robust mechanical interlock with the other adherend, without using conventional adhesives. By tuning pore geometry, this method enables a detachment strength of over 7 MPa, showing significant improvement compared with unstructured interfaces. Experiments and simulations reveal that the fracture toughness stems from a stiffness difference within the interlocked structure, suppressing crack propagation. This structural design strategy offers a rational route to engineering durable interfaces, enabling advanced composites of various materials.