In one of the rare cases of biology-meeting-physics, scientists have noticed that the bodies of some types of insects can repel water and oil. Evolution has also led to some insects being able to adhere to different surfaces and eliminate light reflections. By researching the mechanisms that impart these properties and reproducing them to design materials a potential antifogging breakthrough has been achieved.
The new study has been performed at the ESPCI Paris Tech, École Polytechnique and it has looked at nanotextures, particularly the production of nanoscale textures in a variety of inorganic materials such as silicon, glass and plastics. Nanotextured surfaces are in various forms like cones, columns, or fibers.
Inspiration for antifogging surfaces came from the small hairs located on the bodies of insects that are designed to repel water. Water repulsion happens through the trapping of air. The hairs are called cilia.
Taking the principles to materials science the researchers have created ‘block copolymers’. These are chains of two distinct molecules linked together. Once a series of the polymers are linked together they self-assemble into ordered patterns with dimensions measuring only tens of nanometers in size.
The latest research has looked at how changing the shape of the textures from cylindrical to conical alters how material repels water. Here it was found that cone-shaped nanotextures are more efficient for forcing water droplets off a surface. While removing water droplets is of great use, it does not mean the material is no longer prone to fogging. Fogging happens as warm and most air strikes a cooler surface and condensation develops.
To overcome this, the researchers continued to study insects. With this they noted that nanosized cone-shaped textures on insect cilia can repel fog by causing water droplets to spontaneously jump off their surface. By altering the naotexture of the materials like glass further, the researchers created a surface to which warm drops of moisture cannot adhere. This happens because the condensing water droplets are now too large to penetrate the texture.
The research has been published in the journal Nature Materials, under the title “Antifogging abilities of model nanotextures.”
