Substrate Remote Control of Polymer Film Surface Mobility
Résumé
Polymer segments at the surface of glassy polymer films remain mobile at temperatures below the glass transition temperature, Tg. This mobility, which is usually attributed to the access to a larger free volume by segments at the surface, opens pathways for polymer surface structuration by the effect of a destabilizing force. By studying the destabilization of polystyrene films under the influence of ions dissolved in degassed water at temperatures well below Tg, we have observed that this mobility can be strongly affected by a substrate buried down distances of the order of the chain size below the film surface. This effect is particularly important if there is a strong interaction between the polymer and the substrate or in the presence of pinning points for the polymer chains. These results can be qualitatively interpreted in terms of the sliding model for Tg reduction in thin polymer films. This effect allows remotely controlling the structuration of the polymer surface.