# Advanced Micro/Nanocapsules for Self-Healing Coatings
## 3 Self-Healing Coatings Based on Additives Including Healing Agents
The outcome of this study revealed that microcapsules that had been modified with GO demonstrated a spherical shape with a mean diameter of 0.5 \(\upmu\)m. The obtained microcapsules had excellent thermostability as well as good mechanical properties with respect to Young's modulus, hardness, and load. Finally, the corresponding epoxy coating, including the above microcapsules, presented improved anticorrosive self-healing efficiency. The reason for the enhanced anticorrosive and barrier properties was attributed to the GO nanostructure, which hindered the penetration of aggressive species through scratches and defects. [PERSON] et al. considered the effect of supercritical emulsion extraction technology in order to fabricate microcapsules based on polymethylmethacrylate/diglycidyl ether of bisphenol A [35]. These microcapsules were able to act as a health-monitoring element. They had a spherical shape together with a smooth surface and a mean size of 220 nm and enhanced encapsulation efficiency. The health-monitoring liquid epoxy formulation, used in microcapsule preparation, was accomplished by homogeneously mixing a reactive diluent with a bifunctional epoxy resin. Then, a dye was added to this mixture under stirring. The results revealed that the produced capsules could be broken under stress, resulting in the release of the dye from the microcapsules. Self-healing coatings, particularly those incorporating various healing agents, represent a significant advancement in the realm of material science, promising to mitigate the detrimental effects of environmental factors and enhance long-term durability. These coatings are designed to address the pervasive issue of metal corrosion, which has far-reaching economic and environmental implications. By integrating smart self-healing mechanisms, the coatings can autonomously repair damage, thereby extending the lifespan of the protected materials and reducing the frequency of maintenance interventions [25; 36]. Notably, the efficiency of these coatings is heavily influenced by the type and functionality of the healing agents used. For instance, microencapsulated healing agents in organic coatings have shown considerable promise in autonomously restoring the integrity of the material upon damage [37]. This self-repair capability not only enhances the durability of the coatings but also contributes to the sustainability of the structures they protect by minimizing resource consumption and waste generation [38]. However, despite these advantages, the application of self-healing coatings is not without limitations. Factors such as the compatibility of healing agents with the coating matrix and the potential long-term stability of the healing system under various environmental conditions remain areas of ongoing research and development [39]. Therefore, while the current advancements in self-healing coatings are promising, further studies are essential to optimize their performance and ensure their effectiveness in diverse real-world applications. Self-healing coatings based on healing agents are considered a promising route to acquire more reliable and durable surface protection. The technology is still under development, with ongoing research paying attention to improving the effectiveness, efficiency, and economic feasibility of the aforementioned systems.