A Wayne State
University Professor has developed a material with unique self-cleaning
properties that may serve a number of applications from self-cleaning automobile
windshields, eyeglasses and optics to laboratory glassware, mirrors and sensors.
Highly water-repellant materials (also known as Super Hydrophobic Surfaces) have
been created and employed in a number of applications. However their widespread
use to date has been hampered by the fact that such materials are generally
non-transparent. As such these materials have not been suitable for windows
windshields, camera lenses and other optical devices.
The material
developed at the Wayne State University College of Engineering has the unique
property of being completely transparent and as such could be used in
applications which to date have not been served by opaque super hydrophobic
materials. The invention is a new material structure capable of repelling water
and self-cleaning as well as its fabrication methods. Liquid repellency of solid
surfaces is critical for many applications including the prevention of the
adhesion of moisture and ice to windows, self-cleaning traffic indicators,
stopping clotting in artificial blood vessels and stain-resistant textiles.
The hydrophobicity of
a surface can be enhanced by a chemical modification that lowers the surface
energy. A super hydrophobic surface results from the increase of the surface
roughness. This effect can be observed in nature on the leaves of the sacred
lotus. The surfaces of these leaves have micrometer-scale roughness (10-100 µm)
resulting in water contact angles up to 170° because air that is
trapped between the droplets and the wax crystals at the plant surface minimizes
the contact area. Super hydrophobic surfaces that have water contact angles
larger than 150° have been obtained by controlling the surface topography of
expensive hydrophobic materials using various processing methods such as
machining and etching. Since all these surfaces have micrometer-scale roughness
they are not optically transparent due to diffraction scattering.
Commercial
Applications
• Devices with
transparent surfaces in need of moisture prevention: windows, windshields,
camera lenses, other optical devices
• Liquid repellency on solid surfaces
such as traffic indicators, artificial blood vessels and stain-resistant
textiles
Competitive
Advantages
• Repelling of water
and self-cleaning of transparent surfaces
Patent
Status
Patent
Published