Typical self-healing materials-their mechanism and emerging applications

Abstract

Any biological system in the world has its own mechanism of response towards cuts and cracks. Whenever there is an injury, it appears as wound and the biology starts the inflammatory (immediate) response followed by cell formation and matrix remodeling. This is kind of a long-term process. It provides perfect healing in the biological system (such as human-bodies, plants, trees etc.). Considering this phenomenon as the source of inspiration, a new kind of materials have been developed, which can response to the damage by their self and repairs known as ‘self-healing ’materials. Whenever and wherever the damage (crack, cut, rupture etc.) appears in the material, it triggers the healing mechanism and repairs the damage cracks or notches by chemical repair. This is kind of short-range process than biological one. To date, self-healing is demonstrated mainly in polymers and composites by three conceptual approaches namely capsule based healing system, vascular healing system and intrinsic healing system. It can be automatic without human intervention or may require some external energy or pressure. The synthetic self-healing systems work as three-step process. The first response towards the damage is triggering (actuation). The second response is transport of materials to the site of damage. The third response, analogous to matrix remodeling. This is the chemical repair process. Application of the self-healing martials is expected in all fields of science in the future. The very few developed applications to date are mainly in automotive, aerospace and building industries. An attempt has been made to discuss the mechanism of typical self-healing materials and their emerging applications.