Desorption of polymers: role of the stagnant layer

The desorption of polymers is studied theoretically and with Monte Carlo simulations. Two regimes can be distinguished: in one regime the detachment of the polymer from the surface is the slowest process, and in the other it is the diffusion of the polymer away from the surface. In both regimes the desorption rate depends on the thickness H of the stagnant layer, i.e. the layer in which the polymer movement is dominated by diffusion. In the diffusion-limited regime the desorption rate scales as H - 2 , as expected for diffusive processes. In the detachment-limited regime the desorption rate scales as H - 1 . The importance of the thickness of the stagnant layer in the detachment-limited regime is due to the fact that the polymer, after it has detached, will most likely readsorb soon after: the probability that the polymer does not readsorb, but crosses the stagnant layer, is inversely proportional to the thickness of the stagnant layer