The term functional coatings has been used as a buzz word in the industry just like smart phones in the tech industry. Functional coatings are described as the coatings which have special properties and give the surface many additional functions. Though there are many types of functional coatings, this article will focus on those which are starting to gain some market attention.
Self-cleaning coatings are those coatings which do not allow dust particles to settle on the surface. These types of coatings are based on one of the following two technologies. The first is superhydrophobic coating where water contact angle is greater than 140 degrees. The second is superhydrophilic coating where water contact angle is approximately zero degrees. Superhydrophobic coatings work on the principle of photocatalysis — TiO2 has become a potential candidate exhibiting photocatalytic activity and it is widely used because of its non-toxicity, availability, cost effectiveness, chemical stability, favourable physical and chemical properties.
Self-healing refers to the ability of materials to repair damage automatically without any additional external measures. Other terms for this behaviour are self-repairing, self-recovering, and autonomic repairing. Self-healing coatings are advancing along a similar trajectory — microscopic capsules embedded in coating matrices contain healing agents that when cracks form, capsules rupture, releasing healing compounds that polymerise and repair the damage, extending service life dramatically.
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