KINETICS OF POLYMER ADSORPTION AND DESORPTION

We study adsorption-desorption kinetics of polymer chains at a solid surface. Protio polystyrene, adsorbed from cyclohexane to a single surface of oxidized silicon, was displaced by deuterio polystyrene. A single time constant, tau-off, described displacement for a significant time (1-2 h). An aging effect, in which tau-off continued to increase even after mass adsorbed had equilibrated, implied surprisingly slow rearrangements of adsorbed chains in the direction of conformational equilibrium. After equilibration, tau-off increased exponentially with length of adsorbed chains.