Structure of sodium 4-(1-pentylheptyl)benzenesulphonate aggregates in water solutions by small angle X-ray scattering

The formation of oblate micelles, vesicles, and very flexible bilayers in the region of the phase diagram between micellar and lamellar phase of the binary double-chain ionic surfactant Sodium 4-(1-pentylheptyl) benzenesulphonate/water system was observed. Small angle X-ray scattering (SAXS) with Kratky Compact Camera, and in addition, freeze-fracture transmission electron microscopy (FFTEM), for the determination of the shape and size of particles were used. The maximum dimensions of oblate micelles determined by SAXS were found to be 10–12 nm what corresponds to 12–16 nm from FFTEM images. The axial ratio of the oblate micelles is about 2:1.