Desorption Dynamics of Polymer Adsorbed Layers

We report on the desorption process of polystyrene (PS) from its host, an adsorbed layer on oxide-covered silicon, at a moderate temperature of 120 °C. Measurements were conducted on deuterated polystyrene (<i>d</i>-PS) adsorbed on SiO₂ beneath layers of hydrogenated PS of varying thicknesses (<i>h</i>_top). To assess the desorption dynamics, we measured the width of the broadening <i>d</i>-PS profile (σ_<i>z</i>) and the concentration of <i>d</i>-PS on the sample surface after 20 days of annealing. We found clear evidence that desorption occurs at 120 °C and is enhanced when the thickness of the upper PS layer decreases below ∼45 nm. A model based on surface-enhanced chain desorption accurately describes our data.