A nanoscopic coating whose main function is to protect the surface from the water and repel it is called super hydrophobic coatings. In recent times, many super hydrophobic surfaces have captured the attention of scientists and they have extended their researches on those surfaces in order to obtain the same material which can be used to repel any type of liquid.
Super hydrophobic coatings have a lot of practical applications where it protects the coated equipment or material from corrosion, contamination prevention and protection from other hazardous chemicals. The water repellency of the surface is the important factor to be considered here because a super hydrophobic surface is that surface whose water contact angle is more than 150 degrees. There are plenty of super hydrophobic surfaces in nature, including lotus leaves, butterfly wings, duck feathers, etc. Inspired by nature, super hydrophobic surfaces can be derived by employing two approaches. In the first approach, the solid surface is chemically enhanced with a low-surface material. In the second approach, nano and micro-scale structures are created on the layer to stop water from completely being in contact with the surface.
Super hydrophobic coatings have much application today in many industries but more importantly in maritime industries. They prevent the growing of unwanted micro organism on the hull of the ships and helps in increasing the speed of ships which in turn will reduce the fuel costs. Apart from that, super hydrophobic coatings have usage in automotive industries where these are used on the windshield of the cars to prevent the water clogging. In medical industry, these coatings are also used in surgical instruments due to their extreme resistance and anti bacterial properties. Super hydrophobic coatings depend greatly on a delicate micro or nano structure for their repellence—these surfaces are easily damaged by abrasion or cleaning; therefore, the coatings are mostly used on things such as electronic components, which are not prone to wear. Objects subject to constant friction like boats hulls would require constant re-application of such a coating to maintain a high degree of performance.
The common base used for super hydrophobic coating is silica due to the reason that silica is gel based and can be used on almost all of the surfaces. The other one which is called oxide-polystyrene has a much lasting effect than gel based coatings and is super effective in protecting the surface from corrosion and other unwanted intrusion of chemicals but the cost involved in manufacturing is too high and is not economically viable. This leaves gel leaves based coatings to be the most popular, convenient and effective method to be used.