Wetting is an important interfacial phenomenon that occurs in our daily lives. It is closely
related not only to the academic field of surface science, but also to a wide range of industrial
fields, including textile processing (cleaning, dyeing, and finishing), construction materials,
cosmetics, and electronics components.
It is related to the above.
A lot of research has also been done on water- and oil-repellent processing as a
functional modification of the surface of fibers and polymer films. The contact angle ÿ of a
liquid droplet is widely used as an intuitive index of the wettability of a solid surface, due in
part to its ease of measurement. Generally, water repellency (hydrophobicity) is defined as
a contact angle ÿ of a water droplet of 90° or more, but recently, a contact angle of ÿ between
110° and 150° has come to be called highly water-repellent, and when it is 150° or more, it
has come to be called superhydro-phobic.1) Superhydrophobicity is closely related to the
development of swimsuits, which has been a hot topic, and is also used in the fields of
electronics and energy.
This is a recent topic in the field of wetting, attracting attention in devices, etc. In this article,
we will briefly explain the principles and introduce recent research progress.