Research and development in self-healing materials has increased greatly in the past decade. Self-healing coatings are coatings that are able to heal or repair themselves automatically and autonomously without any external intervention.1 Their investigation have largely been inspired by fracture healing that occurs as a self-repair process in nature.
They are desirable for numerous industrial applications as they can increase materials lifetime, reduce replacement and labour costs, improve product safety and disruption associated with the recoating of surfaces. The automotive, aviation and aerospace, military industries are just a few that will benefit from their development.
The most widely commercialized self-healing coatings are polymer nanocomposite coatings that heal both surface scratches and mesoscopic damage (e.g., micro-cracks and cavitation). These have been applied in automotive coatings, marine surfaces and consumer electronics.2
US-based company Autonomic Materials (www.autonomicmaterials.com) is developing self-healing coatings based on microencapsulated self-healing additives. They are mainly targeting the $700-900 million plus anti-corrosion coatings market.
The next generation of self-healing coatings may be based on microvascular networks and mechano-responsive polymers. Researchers at the Beckman Institute’s Autonomous Materials Systems (AMS) Group at the University of Illinois at Urbana-Champaign have developed 3D vascular networks within fiber-reinforced composites, that allow for continuous cycles of self-healing.3
Microvascular networks have also been developed by researchers at North Carolina State University for dye-sensitized solar cells (DSSCs). These networks can repair prevent the organic dye molecules from degrading and losing efficiency.4
Also under development in a number of research groups are polymers that possess enhanced mechanical properties and are also capable of sensing damage and self-healing.5 6 Researchers at Case Western University have developed mechanically stable self-healing polymer films in response to variety of stimuli.7
References:
1. Gosh, S. K. Self-healing Materials: Fundamentals, Desing, Strategies, and Applications
2. Self-Healing Anticorrosion Coatings, http://www.nstcenter.biz/docs/pdfs/mr2009/proceedings_mr2009-15-fallen.pdf
3. Continuous Self-Healing Life Cycle in Vascularized Structural Composites , http://onlinelibrary.wiley.com/doi/10.1002/adma.201400248/abstract;jsessionid=AA9B7F6FB5D3C4FCBC1CB23FFF242633.f03t01
4. Regenerable Photovoltaic Devices with a Hydrogel-Embedded Microvascular Network, http://www.nature.com/srep/2013/130805/srep02357/full/srep02357.html
5. Mechanoresponsive Healable Metallosupramolecular Polymers, http://pubs.acs.org/doi/abs/10.1021/ma4017532.
6. Tunable mechano-responsive organogels by ring-opening copolymerizations of N-carboxyanhydrides, http://pubs.rsc.org/en/content/articlelanding/2014/sc/c3sc52504j#!divAbstract
7. “Structurally dynamic polymers: From optically-healable materials to mechanically-adaptive films.” , http://www.columbia.edu/event/chemistry-colloquium-stuart-rowan-62933.html
