Counterion distribution in urchinlike charged copolymer micelles Monte Carlo simulation and small angle x-ray scattering

The distribution of counterions inside urchinlike charged copolymer micelles is investigated using Monte Carlo simulation. Each highly charged arm of the micelle is fixed in a rodlike geometry. Three different categories can be distinguished in the counterion population: ions locally condensed in the vicinity of the stretched branches, ions trapped inside the globular micelle and free ions localized outside the micelle which monitor the osmotic pressure and the long range electrostatic repulsion between micelles. Comparisons with simple Poisson-Boltzmann theories in various geometries and with small-angle x-ray scattering confirm this picture. (C) 2003 American Institute of Physics.