Adsorption and desorption kinetics of polyelectrolytes on planar surfaces

A theory of adsorption and desorption kinetics for polyelectrolytes on a planar surfaces in the framework of the Arrhenius-Eyring-Lucassen-Reynders and Nernst-Planck approaches has been developed. It is shown that the. total electrical potential in the double layer must be found only from the integral form of the charge-balance equation in the double layer. Equations were derived to calculate (a)the equilibrium adsorption, (b) the thickness of the adsorbed and double layers, (c) the rate constant for adsorption and desorption, (d) the effective diffusion coefficient in adsorbed and double layer, (e) the activation energy of the polyelectrolyte adsorption (or the enthalpy of polyelectrolyte adsorption), and (f) the time needed to attain the equilibrium state for the adsorption and desorption processes of polyelectrolyte on a planar surface. The adsorption and desorption of water-soluble polyelectrolytes on silicon wafers were studied by ellipsometry.