Hyderabad: Water repellent structures have been developed by IIT Hyderabad researchers by using fly ash, an industrial waste that is much cheaper than the super hydrophobic materials which are available in the market.
The researchers have looked at natural structures which mimic the characteristics of lotus leaves and rose petals. This is because the wax-coated lotus leaves allow water to drip and rose petals hold the water while not allowing it to drop even if the petal is turned over.
These natural characteristics have been mimicked in fly ash which is an industrial waste product and also helps in better waste management.
Dr Mudrika Khandelwal, one of the researchers, said: “The water repellence properties of the lotus leaf and rose petal have been known for a long time. Scientists have explored ways in which these structures can be made artificially for various applications. Mimicking natural structures for engineering applications was not easy. In order to artificially replicate a natural phenomenon, scientists must understand the relationship between the natural structure and the purpose it serves.”
The manner in which lotus leaf repels water is different from that of rose petals. Differences in the structures show that the surface of the rose petal consists of microstructures that have larger spacing and smaller density of nanostructures than the surface of lotus leaf which has a larger area.
Attempts to replicate super hydrophobicity of nature involved altering the water adhesion behaviour of surfaces. Existing methods use costly materials or sophisticated instruments or suffer from scalability issues.
IIT-Hyderabad researchers therefore looked at cheap materials that can be modified to obtain different water adhesion properties.
This new material from fly ash has shown that it has significant use in anti-fouling paints, anti-sticking surfaces for antennae, self-cleaning coatings for automobiles, stain-resistant textiles and anti-soiling architectural coatings.
Researchers stated that the water repellent product was much cheaper than other super hydrophobic coatings developed so far.
Dr Atul Suresh Deshpande, department of materials science and metallurgical engineering at the IIT, and one of the researchers explained, “The particle size of fly ash is between 100 nanometres to a few micrometres, a size range that is suitable for generating rough surfaces that are hydrophobic. However fly ash itself is not water repellent and therefore we coated stearic acid on the fly ash particles which have not allowed the water to go away or seep inside the surface.”
These new coatings can be used to protect concrete structures from rain and moisture-induced damage. They can also be used for water harvesting applications.
