Ksenija Kogej,^a Elisabeth Theunissen,^b and Harry Reynaers^b
aFaculty of Chemistry and Chemical Technology, University of Ljubljana, SI-1000 Ljubljana, Slovenia
^bDepartment of Chemistry, Catholic University of Leuven, Celestijnenlaan 200F,
B-3001 Heverlee, Belgium

Abstract
Synchrotron X-ray scattering was used for structural investigations in systems of sodium poly(styrenesulfonate) (NaPSS) and dodecyl- (DPC) and cetylpyridinium chlorides (CPC) at various surfactant to polyelectrolyte (S/P) molar ratios. From the Bragg peaks emerging in the scattering curves two types of organization of surfactant in conjunction with the polyion are proposed. In NaPSS/DPC (all S/P values) and in NaPSS/CPC complexes (S/P =< 0.7) the surfactant is aggregated into spherical polyelectrolyte-induced micelles. These micelles are smaller in size than the ordinary ones. By increasing the S/P ratio, they grow in size, whereas the number of micelle-like aggregates per polyion-chain remains approximately constant. In the NaPSS/CPC precipitate (S/Pł1) a hexagonal phase is observed with a unit cell constant equal to 39.5 A in which micelles change into a cylindrical shape. No similar crystalline-like structure was observed in complexes with DPC.