SMALL-ANGLE NEUTRON-SCATTERING STUDIES OF CHLORPROMAZINE MICELLES IN AQUEOUS-SOLUTIONS

We analyze small-angle neutron scattering (SANS) data for aqueous (D2O ) solutions of chlorpromazine hydrochloride, with and without a 0.025 m (mol/kg) NaCl solution added. This product is a tranquilizing drug b ased on the phenothiazine ring system, which gives ionic micellar solu tions characterized by pronounced interparticle correlations, resultin g from a strong electrostatic interaction between the macroions. The m odel for fitting SANS data takes into account the effect of size polyd ispersity on the intensity distribution function I(Q) and computes the intermicellar structure factor by the generalized one-component macro ion theory (GOCM) (ref 1), solving the Orstein-Zernike equation in the rescaled mean spherical approximation (ref 2) and considering a scree ned Coulomb interparticle interaction potential between micelles, foll owing the procedure giving in ref 3. SANS fittings for different conce ntrations allow us to obtain some structural and thermodynamical param eters like the free energies of formation and growth, the minimum aggr egation number, and the polydispersity index.