Page "Hydrophobe" Paragraph 32

An example of a biomimetic superhydrophobic material in nanotechnology is nanopin film.

In one study, a vanadium pentoxide surface that can switch reversibly between superhydrophobicity and superhydrophilicity under the influence of UV radiation is presented.

According to the study, any surface can be modified to this effect by application of a suspension of rose-like V < sub > 2 </ sub > O < sub > 5 </ sub > particles, for instance with an inkjet printer.

Once again hydrophobicity is induced by interlaminar air pockets ( separated by 2. 1 nm distances ).

The UV effect is also explained.

UV light creates electron-hole pairs, with the holes reacting with lattice oxygen, creating surface oxygen vacancies, while the electrons reduce V < sup > 5 +</ sup > to V < sup > 3 +</ sup >.

The oxygen vacancies are met by water, and it is this water absorbency by the vanadium surface that makes it hydrophilic.

By extended storage in the dark, water is replaced by oxygen and hydrophilicity is once again lost.