Self‐Healing Materials are Coming of Age

Abstract

While natural materials such as bone or skin are able to heal themselves in an autonomous manner after mechanical damage, traditional man-made materials generally lack this intrinsic capacity for self-healing. In 1969, self-healing properties were for the first time built-in inside polymeric materials[1] and in the following decades publications about self-healing in thermoplastic and cross-linked systems and concrete appeared.[2] Although, it was only in 2001, through an article about self-healing in polymer based materials published in Nature, that research in the field of self-healing materials research was really triggered.[3] By restoring their functional properties autonomously after damage, self-healing materials would offer tremendous advantages over traditional materials in application areas such as civil, chemical, electrical, aerospace, automotive, and biomedical engineering. Autonomous self-healing does not require an external trigger (like heat or irradiation), whereas non-autonomous self-healing only occurs in response to such external triggers.[4] Another classification of self-healing materials is based on the incorporation of separate healing agents (extrinsic self-healing) as opposed to intrinsic self-healing which proceeds without the need to include separate healing agents.[4] Irrespective of their classification, self-healing of materials requires the creation of a local mobile phase which can close and repair cracks by physical flow into the crack and subsequent reformation of chemically stable interfaces.