Free-standing mesoporous silica films with tunable chiral nematic structures

With the beetles: new chiral nematic materials In the natural world, some beetle shells exhibit iridescence due to the chiral organization of chitin that makes up the beetle's exoskeleton. Inspired by the design principles seen in beetle shells, Mark MacLachlan and colleagues fabricate thin glass films with helical pores introduced using a renewable cellulose template. The chiral structure allows the material to selectively reflect light at a specific wavelength; the wavelength can be tuned across the entire visible spectrum by altering the ratio of silica to cellulose during synthesis. The material can be free-standing, and absorption of water renders the structure immediately colourless, although colour is restored once the material is dried out. The novel combination of properties in these materials — chirality, mesoporosity and photonic properties — means that they may be useful in a variety of applications, such as new coatings, smart windows, sensors and displays.