Statics and dynamics of homopolymer adsorption and desorption: A Monte Carlo study

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Abstract
We present results from an extensive lattice Monte Carlo study of the adsorption and desorption of homopolymer chains from semidilute solution onto a solid/liquid interface. We have studied in detail the growth, equilibrium structure and dynamics, and rinsing of layers of homopolymers adsorbed from solution. For solution concentrations at or near the overlap threshold we directly verify the self-similar structure of the adsorbed layer first predicted by de Gennes. This scaling result is confirmed without our having to make any assumptions or inferences as required in experiments. By following the flight of the individual chains, we obtain a detailed description of their structure and dynamics, including direct proof that the adsorbed chains form two broad categories: a tightly bound category with a long characteristic time of exchange with the solution, and a loosely bound category with a very short characteristic time of exchange. We study the differing conformations of these two subpopulations, as well as the kinetics of chain exchange between the adsorbed phases and the bulk solution. Finally, we examine the active displacement of the self-similar adsorbed layer by a solution of different chains. We describe different regimes of desorption, characterized by exponential and faster than exponential decays of the adsorbed layer.