Temperature-gradient–induced instability in polymer films

We report the experimental observation and a theoretical model for a thin-film instability caused by a temperature gradient. A polymer-air double layer sandwiched between two plates set to different temperatures shows an instability leading to polymer columns or stripes spanning the two plates. The characteristic wavelength of these patterns scales inversely with the initial heat flux through the double layer. Theoretically, we describe the heat flow in terms of the diffusion of heat through the bilayer, causing an interfacial radiation pressure that destabilizes the film.