Relationship of photochemical and dynamic behavior of an amorphous photochromic polymer containing azobenzene moieties in the side group

An amorphous copolymer with photochromic azobenzene moieties in the side chain is investigated by UV/Vis and real time dielectric spectroscopy. The aim of this study is to monitor both the reversible E/Z isomerization of the dyes and the influence of the photoreaction onto the matrix. The change of the absorbance and of the dielectric function is measured for the E/Z and the Z/E isomerization. To compare the results model functions are fitted to the measured data and the obtained parameters compared for both experiments. So a correlation between the two spectroscopic methods is established. This analysis leads to a model of the molecular mechanism which is based on excess free volume generated by the photoreaction.