Short range order of rodlike polyelectrolytes in the isotropic phase

The local order of aqueous solutions of rodlike polyelectrolytes is analyze d. It is shown that the scaling of the full width at half-height of the fir st peak of the static structure factor with the concentration C of polyelec trolyte is similar to the scaling of the peak position of the first maximum : it changes from C-1/3 to C-1/2 as C varies from the dilute to the semidil ute regime. This result enables us to estimate the number of ordered next n eighbor shells, N, arranged locally around a central particle. It is shown, in goad agreement with Monte Carlo results, that N similar to 1 when the i onic strength of the solution, I, is similar to 10(-7)-10(-5) M and the pol yelectrolyte surface charge in the solution, Q, is on the order of hundreds of electrons. This order decreases when I goes to similar to 10(-3)-10(-2) M and Q decreases by 1 order of magnitude.