**3. Conclusion**

Self-healing materials are able to heal themselves when damaged, restoring initial properties fully or partially. Inspired by natural mechanisms, self-healing mechanisms have been explored for all types of materials, including metals, polymers, ceramics, and composites.

In the last decades, great progress has been made in the design and development of self-healing polymeric materials and the existing self-healing polymers are considered smart materials able to recover their properties autonomically or nonautonomically. These materials have been suggested for a series of applications such as water membranes, lithium batteries, energy transducers, biomedical devices, flexible electronics, and soft robotics [48].

Ideal self-healing polymers cannot significantly decrease the initial properties of the virgin material. In addition, the methods to assess the healing agent efficiency still need to be better standardized.

Self-healing materials are a new class of smart materials and have attracted a significant interest for research. Several self-healing techniques have been developed and investigated in the last decades. All techniques developed are reported as promising but they also presented with limitations and downsides. Adjustments are still necessary in order to apply the techniques to industrial scale production. Thus, further investigations and research are still necessary.
