A familiar material with a hydrophilic function. For example, clothes and towels. Due to the hydrophilicity of the cotton used in these products, it is possible to spread water over the surface of the substrate and retain a large amount of water inside.

Hydrophilicity refers to the state in which water adapts to the surface of the material (wet state). Scientifically, the surface of a material with hydrophilic functional groups exhibits hydrophilic performance.

Hydrophilicity can be applied to the surface of aluminum fins in air conditioners for efficient internal heat exchange. Used in various fields, even in invisible places, such as eliminating poor visibility caused by water droplets on the glass surface (e.g. car side mirrors), preventing dry solids from accumulating inside equipment where maintenance cannot be performed frequently, etc. is a widespread feature.

Difference Between Hydrophilic and Hydrophobic

Super hydrophilic stateHydrophilic stateWater repellencySuperhydrophobic state
super hydrophilic conditionhydrophilic conditionWater repellencySuperhydrophobic state
Due to its high hydrophilic effect, water spreads over an extremely wide area, so the function of washing away various stains and anti-fogging effects is enhanced. It is possible to keep the surface of the base material in good condition for a long time.The contact angle at which dirt is washed away with water is about 30 degrees (see the figure above). If the contact angle is greater than that, the water will not spread and the water will partially pool, reducing the cleaning effect.It forms water droplets and stays on the base material surface in a hemispherical state (e.g., Teflon surface). Dirt in the water droplets condenses and easily remains on the surface. (Water marks) It can also cause the surface to become cloudy.When the water droplets become completely spherical, the water droplets on the surface become water repellent enough to fall off. (Example: lotus leaf falling water) The surface is in good condition without water droplets, but it is expensive and difficult to obtain.
Small contact angle    Large contact angle