Sponsored Student: Organically-modified porous coatings for antifogging applications

Transparent optical coatings play an important role in tailoring light. By the use of thin films, it is possible to modify the surface depending on the environmental conditions. Fogging, which is a disturbing effect, occurs when small water droplets adhere to the surface. It reduces the efficiency of optical surfaces and can also create a significant safety risk (e.g. visors and glasses). Hydrophilic or water absorbing materials are theoretically suitable to counteract the fogging. However, these are too soft or not long-lasting enough for most practiceoriented applications. Hence, the chemical compounds realizing the antifogging effect have to be buried deep in the composite material. It therefore neither affects the mechanical stability nor the optical properties of the surface. To obtain a mechanically stable surface with hydrophilic properties, porous oxide layers are generated to function as a reservoir. The incorporation of active organic components ensures the antifogging effect over a long period of time. An additional cross-linking of the organics afterwards improves the mechanical stability. The behavior of organically-modified porous oxide layers was analyzed concerning the optical and mechanical properties and the antifogging. The viscosity of the organic compound was varied and its impact on fogging examined.