Lotus is revered in Asia for its exceptional cleanness. Although it grows in muddy waters, its leaves always appear immaculately clean. Lotus leaves are ultrahydrophobic. If drops of water roll off free of residue, they would take any impurities with them (Figure 1). The self-cleaning property has fascinated many scientists and engineers to mimic and produce a ultrahydrophobic coating.
The self-cleaning coating sounds very helpful to human, but it has big limitations for this coating to be widely use.
The coating cannot apply to anything. Washing clothes consumes considerably large amount of water and water-polluting detergent. We could save large amount of water and use less water-polluting laundry detergent if our clothes are coated with self-cleaning coating. However, the self-cleaning coating is hard to be maintained on any clothes because it gets destroyed easily if it’s being washed in a washing machine.
The coating cannot apply to things anywhere. Because self-cleaning property wopuld only be effective with running water, it is quite restricted to apply it on buildings’ interior. However, cleaning and maintaining interior also consumes a lot of energy and water, the coating cannot really help us be more efficient with energy and environmental-friendly.
Even though it has so many restrictions, it actually can make boats and ferries more energy-efficient because of its ultrahydrophobic property. Coating on boats can largely reduce friction between water and body of boat, and the coating also prevents microbes to grow on boat. We are looking forward technology improvement will solve the restrictions of self-cleaning coating so that we could use this coating more in our daily life to achieve a more energy-efficient society.