selfmending

Selfmending, or self-healing, refers to the ability of a material or system to repair damage and restore function after degradation, with little or no human intervention. The term covers a range of approaches in materials science, infrastructure, and engineered systems that aim to extend service life by autonomously addressing cracks, fractures, or wear.

In materials science, selfmending mechanisms are generally categorized as intrinsic or extrinsic. Intrinsic self-mending relies on reversible chemical bonds or phase changes within the material, such as dynamic covalent bonds, hydrogen-bond networks, or shape-memory effects that reclose cracks upon activation. Extrinsic self-mending uses embedded healing agents, microcapsules, vascular networks, or dispersed particulates that release repair agents when damage occurs.

Concrete is a common focus for infrastructure self-mending, with approaches including bacteria that precipitate calcium carbonate, encapsulated healing agents, or microvascular networks. In polymers and coatings, self-mending systems employ microcapsules containing monomers, epoxy resins, or rejuvenators that flow into cracks and polymerize. Hydrogels, elastomers, and some composites utilize dynamic bonds to restore integrity after damage.

Performance is typically measured by healing efficiency, such as recovery of modulus or fracture toughness after damage, and the extent of crack closure. Challenges include ensuring long-term durability, repeated healing cycles, environmental sensitivity, and cost, as well as integrating sensing and activation mechanisms.

Ongoing research aims to broaden applications, improve multi-cycle healing, and combine selfmending capabilities with sensing and monitoring. Commercialization remains uneven, but selfmending concepts are increasingly pursued for infrastructure, protective coatings, electronics, and textiles.