Self-Healing polymer coatings

Abstract

Traditional coatings made of thermosetting polymers could not be healed or mended because of their cross-linked structure, so damage implied the end of their service life cycle. This picture has dramatically changed since the first self-healing systems reports, moment in which this “disadvantage” of thermosets has started to vanish with the continuous increase in the availability of self-healing and recyclable thermosetting polymers. These advances constitute a breakthrough, as they would avoid replacement and catastrophic failure, encourage recycling and re-processing and prevent the generation of a considerable amount of waste, with obvious environmental and economic benefits. This chapter describes some of the more recent advances in the field of self-healing thermosetting polymers with potential application as coatings. Extrinsic self-healing thermosets use an external agent to perform the healing whereas intrinsic ones require the intervention of an external trigger for repair damage. The first part of the chapter describes the work in extrinsic self-healing thermosets, and the second part in intrinsic ones, with emphasis on polymeric networks with dynamic covalent bonds (DCBs). The most common strategies for the external triggering of intrinsic self-healing polymers are also described. Finally, challenges are discussed with the aim put in attaining the so expected end-user applications.