Why has the lotus plant such unusual properties – the lotus effect?
Different successive layers are visible under the microscope. The outer surface of the leaves has small nubs which are 5-10 micrometers high and 10-15 micrometers separated from each other (1 micrometer is 1 thousandth of a millimeter). These nubs are covered by a fine nano structure of wax crystals with diameters of about 100 nanometers. They consist of a mixture of different water repellent (hydrophobic) plant waxes. Also dead, even dried leaves of the lotus plant show the lotus effect.
Video > how does the lotos effect work?
Video > test with red wine
The contact angle and the effect of repellency
The angle between the surface of the substrate and the surface of the water droplet on it is decisive for the repellency or lotus effect. The contact angle is a measure for the wettability of the surface with water.
Contact angle < 30° - hydrophilic surfaces
On untreated or hydrophilic surfaces the water droplets spread, the contact angle is very small. Water droplets cannot roll off, only glide.
Contact angle approx. 90° – hydrophobic surfaces
The ideal contact angle so that a surface is not only water repellent but can also be cleaned with water.
Contact angle > 120° – superhydrophobic surfaces
Super hydrophobic surfaces are characterized by big contact angles. The actual contact area is only two to three percent of the surface covered by a water droplet. The drop lies as if on a bed of nails made of crayons and touches only their tips. This decreases the attraction between the water and the substrate, the water droplets become round. They slide off at the lowest angle of inclination. The surface does not get wet.
The secret of Nanotol is the contact angle, the borderline of hydrophobicity!
In the development of Nanotol a great effort was made to leave the contact angle large enough to retain the self-cleaning effect but to enable the user to clean the surface with water.
Therefore, surfaces coated with Nanotol are water repellent but do not have an extreme lotus effect. A major benefit is that such surfaces are very easy to clean because water removes dirt and slides off. Video > the Nanotol effect