Self-healing crystals

Abstract

Self-healing is an intrinsically exciting concept as it applies to the process of recovery, a commonplace phenomenon found in living organisms. Self-healing of artificial materials is as beneficial to living creatures as it is to materials science, wherein the effect can considerably prolong lifetimes. Although self-healing sodium chloride crystals were discovered in the 1980s, the field entered a renaissance when healing was observed in the emerging materials class of molecular crystals in 2016. Self-healing properties in polymers, cementitious materials, and coatings have already found commercial applications. The reinvigorated interest in self-healing molecular crystals stems from their prospects as durable, lightweight and flexible emissive or electronic materials. Ideally being defectless and ordered media, organic crystals have unique optical, mechanical and electrical properties, and the possibility of self-healing substantially increases their viability for smart devices. Self-healing crystals are an emerging class of materials that are highly responsive to dynamic stimuli. This Perspective gives an overview of the field since its inception, highlights current design principles, and discusses the methodologies used to characterize healed crystals.