Easily made antireflective coatings for flexible surfaces

Conventional antiglare coatings for eyeglasses, camera lenses, and car headlights are made of thin films of low refractive index materials such as magnesium fluoride. Although they work well, they can be applied only to flat surfaces and are difficult to make over large areas. Now, a simple method to create durable, antireflective coatings could make it easier to produce large, glare-free windows and flexible electronic displays (ACS Appl. Mater. Interfaces 2016, DOI: 10.1021/acsami.6b10624). Norihiro Mizoshita and Hiromitsu Tanaka of Toyota Central R&D Laboratories made the coatings by spraying plastic substrates with nanosized silica beads dispersed in ethanol. After the ethanol evaporated, the researchers exposed the substrates to chloroform vapor, which softened the plastic and allowed the nanospheres to sink into the surface. Washing away excess nanoparticles left behind a single layer of beads embedded about 50 nm deep in the plastic. Coatings made of 190-nm-wide particles reflected 1.2% of visible light, compared with bare plastic surfaces, which reflect 8%. The coatings survived repeated bending and heating-cooling cycles as well as rubbing with cotton wool and attempts to peel off the nanoparticles with adhesive tape.