Self-healing: a new paradigm in materials design

Self-healing materials, when damaged, are designed to sense the failure and respond in an autonomous fashion to restore structural function. Inspired by biological systems, synthetic self-healing materials represent a new paradigm in the design of polymer based composites. This overview article summarizes the different strategies and approaches to achieving self-healing functionality and discusses future directions in the nascent field. The strategies are broadly classified into the following three categories: healing with an embedded liquid phase repair agent, thermally activated solid phase healing, and healing of projectile puncture.