Analytical resolution of the Poisson–Boltzmann equation for a cylindrical polyion immersed in an electrolyte solution: using the optimal linearization method

By using the optimal linearization method (OLM), the potential of the electrical double layer created by a highly charged cylindrical polyion immersed in an electrolyte reservoir, which is represented by the so-called Poisson–Boltzmann equation (PBE), has been solved analytically under general potential conditions. For this system, three regions must be considered. The first one is in the near-neighborhood of the polyion and it is deprived of coions because of the repulsion phenomenon between the polyion and the coions, as proposed by Fuoss et al. (Proc. Natl. Acad. Sci. 37, 579 (1951). doi: 10.1073/pnas.37.9.579 ). For the second region, where the potential is slightly lower, we propose an OLM for solving the PBE. In the last region, where the potential is sufficiently low, the approximation of Debye–Hückel is adopted. This method allowed us to overcome some shortcomings in the analytical calculation of the electrostatic potential created by a polyion in an electrolyte solution.