Structure functions of rod-like DNA fragment and polystyrenesulfonate solutions in the modified Poisson-Boltzmann theory

The partial structure functions of aqueous solutions of rod-like DNA fragments and polystyrenesulfonic acid are calculated in the modified Poisson-Boltzmann theory. The cylindrical cell model appropriate for linear polyelectrolyte solutions with monovalent counterions and without any added salt is utilized. The predicted results are compared with the corresponding results from the classical Poisson-Boltzmann theory, and experimental small angle neutron scattering data obtained in the monomer concentration range 0.05-0.2 mol/dm3. It is seen that both the modified Poisson-Boltzmann and the Poisson-Boltzmann results lead to a very good fit to the experimental structure functions.