Positive weathering results as milestones in the development of thermochromic nanocoatings

Coatings are a large and significant field of application for nanotechnology /1/ - /67/. Particularly important examples are thermochromic nanocoatings. These are characterized by reversibly changing the colour from dark to transparent during a heating process at a switching temperature. This is not only an interesting optical and aesthetic effect, but has its significance in the fact that the absorption- and reflexion behaviour for thermal radiation in the thermal-IR changes. As a consequence, heat is absorbed at low temperatures below the switching temperature and reflected above the switching temperature at higher temperatures. In this way heat-balancing layers can be produced. For applications in architecture as facades and roof claddings, significant energy savings are possible. Since these are external applications, the coatings have to withstand environmental stress. Weathering experiments of all kinds are therefore essential for product development. The paper gives insight into the development of thermochromic systems under special consideration of weathering results.