Cross-scale design of energy dissipative composites using self-repairing interfaces based on sacrificial bonds

New composites with high energy dissipation and self-healing properties are required for structural materials, textiles, and protective equipment. This paper proposes a cross-scale strategy to design sacrificial bond composites (SBCs) using non-linear adhesive materials, like self-assembled proteins or mechanical adhesives, placed between opposite-facing magnets. Upon external loads, SBCs effectively dissipate deformation energy across their sacrificial bond interfaces following a biomimetic toughening mechanism similar to nacre's. When the external load breaks the sacrificial bonds of a SBC, the opposite-facing magnets brings together the separated interface, allowing the reforming of its sacrificial bonds and the self-repairing of the composite after sustaining large strains. After mechanical failure at 600% strain, the consensus tetratricopeptide repeat (CTPR) protein films allows protein-based SBCs to recover 70% of their original tensile strength after letting their sacrificial bonds to reassemble for 1 h, at room temperature, in the presence of moisture. Mechanical adhesive-based SBCs, after their mechanical failure at 325% strain, are able to self-repair faster, regaining 85% of their tensile strength in less than 1 s. As a proof of concept, we demonstrate the fabrication of a reusable and lightweight fall arrest system exploiting mechanical adhesive interfaces and a protein-polyester yarn for the creation of high-energy dissipating textiles.