STUDYING THE MOBILITY AT THE FREE INTERFACE THROUGH SURFACE PATTERN DECAY: EXPERIMENTS ON POLYMERIC FILMS

We studied the time evolution of the dynamics of a (3 kg/mol molecular mass) polystyrene film patterned with a sinusoidal waveform with various wavelengths, spanning a range from μm to hundreds of nm. The analysis of the pattern decay by white light interferometry and atomic-force microscopy techniques, allowed to determine that the viscous flow diffusion controls the surface flattening in a wide temperature range: from the glass transition temperature of the polymer to tens of degrees above it. Moreover, we have simulated the polystyrene dynamics in the glassy state showing that the surface diffusion would overcome the viscous flow in a region some degrees below the glass transition temperature, determining a dynamic decoupling. We have also developed a new procedure through the application of multiple techniques and with the use of different polymers to realize a quasi-sinusoidal molds (PFPE) with an aspect ratio lower than 0.1 and wavelengths spanning from 450 to 4500 nm, to use a master for the patterning of the polystyrene films