BRUSH THEORY OF TETHERED CHAINS WITH A CHARGED GROUP AT THE FREE END

We consider the problem of end-grafted polymer molecules vith a charge d group attached to the free end both by an analytical and a numerical method. In the analytical approach the Gaussian model for the polymer chains is used. In this model volume interactions are ignored and ana lytical solutions for special type of boundary conditions are found. W e consider both a repulsive surface, and a critical adsorption energy surface. The complete Poisson-Boltzmann equation is used and deviation s from local electroneutrality are considered in a perturbation method scheme. It is found that deviations of local electroneutrality both s cale inversely with the chain length (N-1) and inversely with the ioni c strength (Phi(s)(-1)). In the numerical method we apply a self-consi stent-field scheme of freely jointed chains in Theta conditions. Resul ts of the analytical model compare favorably to those obtained by the numerical method.