DYNAMICS OF THE SOL-GEL TRANSITION IN ORGANIC-INORGANIC NANOCOMPOSITES

Two different techniques have been used to follow the gelation of phot ochromic organic-inorganic nanocomposites. The variations of molecular and macromolecular motions in these complex systems have been analyze d. Photo-correlation spectroscopy probes the formation of the gel netw ork. Forced Rayleigh scattering experiences the microstructure of the mixtures via the measurement of the translational diffusion coefficien t of entrapped photoreactive targets. In the different mixtures, a dro p of the network mobility could be observed around the sol to gel conv ersion, while the entrapped molecules do not experience the macroscopi c transition.