Self-healing polymer coatings

ALTUNA, F.I.; HOPPE, C.E.

Self-healing Materials and Their Allied Applications

Wiley/Scrivener

Año: 2021; p. 5 - 38

Traditional coatingsmade of typical thermosetting polymers could not be healed or mended because oftheir cross-linked structure, so damage or break-up used to be the moment ofthe end of their service life cycle. This picture has dramatically changedsince the first self-healing systems reports, published in the late 1970s andearly 1980s. Since then, this ?disadvantage? of thermosets (compared withthermoplastics) has started to vanish with the continuous increase in thenumber of systems based on self-healing and recyclable thermosetting polymers.These advances constitute an actual breakthrough, as they would avoidreplacement and even catastrophic failure which is expected to save lots oftime and economic resources. It would also encourage recycling andre-processing, preventing the generation of a considerable amount of waste,with obvious environmental and economic benefits. This chapter describes someof the more recent advances in the field of self-healing thermosetting polymerswith potential application as coatings. Most popular classification ofself-healing thermosets is between extrinsic and intrinsic healing systems.Extrinsic self-healing implies the use of an external agent to perform thehealing of the damage. Intrinsic ones, on the contrary, do not require theintervention of an external healing agent. The first part of the chapter isdevoted to describe the work in extrinsic self-healing thermosets, and a secondpart to intrinsic ones, with special emphasis on polymeric networks withdynamic covalent bonds (DCBs). In the majority of cases, extrinsic self-healingpolymers are totally or nearly autonomous, and intrinsic ones need an externaltriggering such as heat, light or a mechanical stress. This disadvantage ofintrinsic ones can be overcome using modifiers (metallic and carbon-basednanostructures, among others) enabling remote activation. Hence, in thischapter the most common strategies used for the external triggering ofintrinsic self-healing polymers are also described. Finally, challenges arediscussed, trying to stimulate research in this continuously growing and activefield with the aim put in the knowledge that enable us to attain the soexpected end-user applications