DENSITY INHOMOGENEITIES OF HIGHLY-CHARGED POLYELECTROLYTE SOLUTIONS CONFINED BETWEEN UNCHARGED AND NONADSORBING WALLS

Monte Carlo simulations are used to study the density profile of dilut e and semidilute solutions of highly charged polyelectrolytes confined between uncharged and nonadsorbing walls. We find that the density pr ofile displays oscillations whose wavelength corresponds to that of co rrelations in bulk polyelectrolyte solutions. The amplitude of the osc illations increases with chain molecular weight. The density oscillati ons observed cannot be attributed to the confining walls, poor backbon e solubility, colloidal-like ordering, or nonuniform distribution of c ounterions. We conclude that the correlations in polyeletrolyte soluti ons must be due to a balance between the segment-segment electrostatic interactions and the chains' translational entropy.