Abstract
The photoisomerization of azobenzene in poly(dimethylsiloxane) was measured in a wide temperature range(77-288K). The final cis-fraction for the trans-to-cis photoisomerization of azobenzene indicates no temperature dependence above 180K, a little above Tg of poly (dimethylsiloxane), but it decreases with decreasing temperature below 180K. The kinetic model considering local fluctuation of the free-volume was also adopted to the previous results of photoisomerization of azo-compounds and stilbene in polycarbonate, PMMA, (phenoxy resin and polyvinyl alcohol), and the effects of the size of molecules, the mechanism of photoisomerization, the main chain structures of polymers and the formation of hydrogen bonding on the parameters for the model were discussed.
