STRUCTURE OF WEAKLY CHARGED POLYELECTROLYTE BRUSHES - MONOMER DENSITYPROFILES

The internal structure (the monomer density profiles) of weakly charge d poly electrolyte brushes of different morphologies has been analyzed on the basis of the self-consistent-field approach. In contrast to pr evious studies based on the local electroneutrality approximation vali d for sufficiently strongly charged or densely grafted (''osmotic'') b rushes we consider the opposite limit of sparse brushes which are unab le to retain the counterions inside the brush. We have shown that an e xact analytical solution of the SCF-equations is available in the case of a planar brush. In contrast, to Gaussian monomer density profile k nown for ''osmotic'' polyelectrolyte brushes we have found that weakly charged brushes are characterized by constant monomer density. At the same time free ends of grafted polyions are distributed throughout th e brush. Thus, the structural cross-over between polyelectrolyte ''mus hrooms'' and dense brush regimes is established.