Self-Cleaning Paint

Making materials self-cleaning, so that water forms beads on their surfaces and rolls off taking any dirt with it, may be as simple as applying a coat of paint. Chemists led by Ivan P. Parkin of University College London have created a nanoparticle-based coating that renders cloth, paper, glass, and steel self-cleaning (Science 2015, DOI: 10.1126/science.aaa0946). The paint is an ethanolic suspension of titanium dioxide nanoparticles in two different size regimes coated with perfluorooctyltriethoxysilane. The paint can be sprayed, dipped, or extruded onto various materials. Combining the paint with commercial adhesives led to hardier coatings that maintain their self-cleaning properties even after suffering scratches and abrasions. Although other researchers have created self-cleaning coatings, this one stands out because it still functions when contaminated by or immersed in oil, which tends to rob super­hydrophobic coatings of their water-repelling abilities. This property makes the paint promising for gears and bearings, which need to stay clean to work properly but often come into contact with oil.