Spinodal Dewetting of Thin Polymer Films

Dewetting of polystyrene films on a silicon substrate is investigated as a function of film thickness $h$. We observe the nucleation of holes in the early stage of dewetting for relatively thick films $(h>\mathrm{}100\mathrm{}Å)$, as observed previously, but the breakup of thinner films occurs through the growth of uniformly distributed surface undulations (“spinodal dewetting”). The average amplitude $\delta h$ of these undulations increases exponentially up to the film rupture point where $\delta h$ becomes comparable to $h$, as predicted by a capillary wave instability model.