ON THE THEORY OF GRAFTED WEAK POLYACIDS

We use a self-consistent mean-field (SCF) theory to determine the beha vior of grafted polyacids. In these systems, the charge on a brush seg ment depends on its local environment and on the pH of the solution. T he scaling dependence of the brush height on salt concentration phi(s) is significantly different from that for a brush with constant charge density. In the latter case, the thickness is a continuously decreasi ng function of phi(s), whereas for a brush of weak polyacids the thick ness passes through a maximum. The numerical SCF results show qualitat ive agreement with predictions obtained from a simple scaling model ba sed upon a block profile with a uniform degree of dissociation.