Density distributions of poly (methyl methacrylate) thin films in non-solvents

Recently, polymeric materials nave oeen widely used in applications sucn as medical materiais, in tnese applications, the surrace comes into contact with a different phase. Thus, their interfaces should be studied, both their structures as well as their dynamics. The density profiles of a perdeuterated poly(methyl methacrylate) (dPMMA) film in water, hexane, methanol, ethanol, 1-propanol, and 1-butanol were examined along the direction normal to the interface by neutron reflectivity (NR). Although these liquids are typical non-solvents for dPMMA, the liquid/polymer interfaces were diffuse in comparison with the air/polymer interface probably due to the partial dissolution of polymer segments at the outermost region of the film. Interestingly, in water, an anomalous swollen layer was formed beneath the diffused interface. On the other hand, such a swollen layer was not observed for the dPMMA films in alcohols. This is simply because alcohol molecules deeply penetrated into the films. The amounts of the alcohols penetrated are related to the interaction parameter. The fractional amount of nonsolvents at the substrate interface was higher than that in the internal region of the film.