Changing colours of latex
A new approach to making colour changing, light sensitive materials has been developed by researchers in Scandinavia.
Until now, inorganic-organic materials have only been used to make thin films, but these are not suitable for many applications. Lennart Bergström and colleagues from the Institute for Surface Chemistry in Stockholm, the Norwegian University of Science and Technology, and Stockholm University have incorporated photochromic dyes into silica particles that can be dispersed in latex films, and they have been able to produce films with different thicknesses.
Photochromic materials, like the ones under investigation, are used in protective lenses, optical switches and optical memories. However, their optical properties are often affected by the matrix in which they are dispersed for applications.
Bergström found that their films quickly became red or blue under ultraviolet
light, and returned to colourless when the UV light was blocked. Their approach opens up the possibility to produce photochromic materials with a range of different shapes.
N Andersson et al, J. Mater Chem., 2005 (DOI: 10.1039/b505319f)