The Polyelectrolyte Brush: Implications from Simulation Results on Polyelectrolytes in Solution

Abstract

Simulation results as well as experimental data indicate that full stretching of flexible polyelectrolytes will not occur for experimentally realizable solution conditions. Using density-dependent swelling exponents ν(O) as suggested by Stevens and Kremer (SK) from the results of a MD simulation study of fully ionized polyelectrolyte chains in solution without added salt, we present an Alexander-de Gennes-like scaling picture for the behavior of charged brushes. The brush height is found to become dependent on the grafting density as soon as internal stretching is incomplete, i.e., at ν(O)<1. Due to SK the maximum stretching occurring below a characteristic saturation density is given by ν s =0.90