Instabilities in thin polymer films

Thermal fluctuations of the surfaces of thin polymer films can be amplified by the long-range van der Waals or dispersion forces which acts across the film. When freely-standing polymer films are heated, this instability leads to the formation of holes. It was measured the formation and growth of holes in very thin, freely-standing polystyrene (PS) films to learn about the mobility of the confined polymer molecules. It was also symmetrically capped freely-standing polystyrene films with thin, solid layers to probe the effects of mechanical confinement. During the early stage of dewetting, discrete highly asymmetric holes appear spontaneously throughout the film. The nucleation rate of these holes is faster than their growth rate.