Stability of an Evaporating Thin Polymer Film

Mesoscopic patterns have been observed to form in thin polymer films undergoing a fast dip-coating process. Though several mechanisms for creating of mesoscopic patterns have been proposed, the mechanism of the evaporation-induced mesoscopic self-organization is not yet fully understood. The paper aims to explain this phenomenon by studying the stability of a thin evaporating film. The analysis does not assume long wave disturbances or quasi-steady base solution. It is found that under these conditions there exists a purely thermal instability mechanism that could be responsible for mesoscopic pattern formation. The instability is caused by increasing of evaporation with the film thinning due to higher heat flux from the substrate to the film surface.