Fast swelling kinetics of thin polystyrene films

In situ the swelling of thin polystyrene (PSd) films by toluene is investigated with specular and off-specular neutron reflectivity. Due to the very high time resolution of 30 s, the initial stages of swelling as well as the fast swelling are detected. Followed by a slow swelling and final stages, in total four different regimes are identified until equilibrium with respect to a homogenously swollen PSd film is reached. Film instabilities are avoided in the absence of any motor movements in the time-of-flight mode of the neutron reflectometer D17.