Bio-inspired Self-Healing Materials- A Novel Approach

Abstract

The development and characterization of self-healing polymeric materials have been inspired by biological systems in which damage triggers an autonomic healing response. This is an emerging and fascinating area of research that could significantly extend the working life and safety of the polymeric components for a broad range of domestic as well as defence. Polymers and structural composites are used in a variety of applications, which include transport vehicles (cars, aircrafts, ships, and spacecrafts), civil and defence engineering, and electronics. However, these materials during their use are susceptible to damage induced by mechanical, thermal, chemical, UV radiation, or a combination of these factors. This could lead to the formation of micro-cracks deep within the structure where detection and external intervention are difficult or impossible. The presence of the micro-cracks in the polymer matrix can affect both the fiber- and matrix dominated properties of a composite and it is leads to catastrophic failure of any structure. However, many conventional repair methods are not effective for healing invisible micro-cracks within the structure during its service life. The concept has been demonstrated through US Air force and European Space Agency investments in self-healing polymers. Self-healing materials have the capability of repairing or recovering themselves when suffering mechanically or thermally induced damage, which can occur autonomously or be activated by external stimuli (e.g. heat) once or multiple times. Hollow fiber and microcapsules /nano-capsule approaches are the most studied technological approaches to the development of self-healing polymers. Embedded microcapsules filled with a liquid healing agent ruptured and release the healing agent into the damaged area and react with already incorporated catalyst causes polymerization of the healing agent, thus repairing the damage autonomically. The reversibility of supramolecular interactions makes them well suited for incorporation into a healable material, allowing for a system capable of undergoing multiple cycles of mending. A reverse Diels–Alder approach ensures the reformation of broken bonds on heating. Using this concept the recycling of thermoset-based plastics and composites is possible.