Photochromic sol-gel derived hybrid polymer coatings: the influence of matrix properties on kinetics and photodegradation

Photochromic dyes undergo a reversible change in their absorption characteristics upon UV light irradiation. By incorporating such photochromophores into sol-gel derived inorganic-organic hybrid polymers, versatile coatings with a fast photochromic response and high photochromic activity can be obtained. In the present study, the isomerization kinetics of spirooxazine dyes entrapped in hybrid polymer coatings were investigated in situ. The chemical properties of the matrices used were characterised in terms of their inorganic network connectivity (NMR measurements) and paramagnetic properties (EPR spectroscopy). Their photodegradation behaviour was studied by means of artificial weathering.