Hokkaido University Research Profiles

Nanotechnology / Materials

Fabrication of High-speed Superhydrophilic Surfaces and Sliding-controlled Superhydrophobic and Superoleophobic Surfaces

Both water and oil can soak well into the surface, slide off it easily, and stick to it properly

We will show you how to create superhydrophilic surfaces that can rapidly be wetted and covered in water, and superhydrophobic and superoleophobic surfaces that repel water/oil very well although their sliding behavior can easily be controlled to allow water/oil to be adsorbed on the surface or easily slide off.

Content of research

Anodizing is a technique used to form oxides with various nanostructures on the surface of metals. We have developed a method to form a large amount of nanofiber oxides with a diameter of sub-10 nm (10 nm or less) by anodizing using a novel electrolyte chemical species. The density of nanofiber formation is extremely high, in the order of 1010 nanofibers (10 billion nanofibers) per cm2. We have found that the metal surface formed with such high-density nanofibers exhibits fast superhydrophilicity of one second or less, as well as superhydrophobicity and superoleophobicity with controlled sliding behavior. It is also possible to mix surfaces with different wettability by using micropatterning techniques.

  • Superhydrophilic, superhydrophobic and superoleophobic surfaces

  • Superhydrophobic surface with controllable sliding behavior

Potential for social implementation

  • ・Energy devices such as heat exchangers and solar power generators
  • ・Microfluidic technology
  • ・Surface technology
  • ・Nanotechnology

Appealing points to industry and local governments

Changing the surface of a material can drastically change the properties of the material. A varied degree of wettability can be created on material surfaces, such as a surface that can be wetted very well, a surface that repels water and oil but adsorbs them easily, and a surface from which they slide off quickly.