Effect of solvent quality on polyelectrolyte adsorption at an oppositely charged surface

The effects of the solvent quality on the adsorption of weakly charged poly electrolytes at an oppositely charged surface are investigated using the se lf-consistent mean field theory. The analytical solutions of the self-consi stent field equations are obtained in the case of theta, good and poor solv ents for the polymer backbone. Using these analytical solutions the thickne ss of the adsorbed layer is calculated as a function of the surface charge density, salt concentration, and solvent quality. It is shown that for poly electrolyte adsorption from theta and good solvents the surface charge is a lways overcompensated by adsorbed chains. For low ionic strengths the surfa ce overcharging is inversely proportional to the Debye screening length. Ho wever, in the case of adsorption from a poor solvent the adsorbed polyelect rolytes undercompensate the surface charge. (C) 2001 American Institute of Physics.