Superhydrophobic substances have recently gained the spotlight because of their potential to be employed in a variety of smart applications such as self-cleaning, anti-icing, heat reduction, drag minimization, and oil-water separation. The traditional technique to prepare superhydrophobic materials is by amalgamating surface micro/nanostructures with low energy surface chemistries. However, material prepared via this route has various drawbacks such as low durability as they are more exposed to chemical/mechanical erosion. To overcome this difficulty, the self-healable superhydrophobic surface is fabricated that can autonomously restore the surface phenomena and liquid repellency, once the surface hydrophobicity is eroded. Healing agents like fluoroalkyl silane, perfluorooctyl acid, or octadecylamine have been used as low surface energy healing agents to synthesize smart surfaces for the fabrication of robust superhydrophobic substances. Once the surfaces have been etched, the healing agents can migrate from the inner pores/microcapsules to the surface, thus restoring the original functionalities.
Interestingly, it is not the humans that developed self-healing hydrophobicity for the first time. Several plant leaves (lotus leaves) regenerate their epicuticular wax layer, once it gets eroded. Recently a group of scientists headed by Dr. Tian and Dr. Huang blended the concept of biomimetics with superhydrophobic materials to fabricate Fast self-healing superhydrophobic surfaces enabled by biomimetic wax regeneration. They communicated to use simple replica molding (a special kind of patterning technique used in soft lithography) to synthesize a new superhydrophobic surface by integrating n-nonadecane wax into microstructured poly(dimethylsiloxane) (PDMS) matrix. The swift migration of the n-nonadecane wax molecules (owing to minimize the total interface free energy of the system) from the polymer surface to the eroded provides a dynamic strategy to develop high performing self-healing hydrophobic materials. The self-healing experiments revealed that the regeneration of the superhydrophobic state takes around 20 minutes without the application of any external excitation.
The material is one of the potential candidates to be used as cost-effective coatings for outdoor applications. Moreover, harmonizing the material with stimuli-responsive active agents could lead to more efficient healing attributes. For instance, using sunlight as one of the stimuli may lead to a catalyzed healing mechanism for outdoor coatings when the eroded surface shall the exposed to the environment.
The image was referred from https://www.chemistryworld.com/features/superhydrophobic-materials-from-nature/3010321.article