Surface and solid-state properties of a fluorinated polyelectrolyte-surfactant complex

The complexation of poly[(acrylamidopropyl)trimethylammonium chloride] with sodium [bis(perfluorohexylethyl)-2-sulfosuccinate] (Fluowet SB) in aqueous solution results in a highly ordered mesomorphous polyelectrolyte-surfactant complex. Films prepared from the complex exhibited a remarkably low critical surface tension of 6 mN/m, which was determined by dynamic contact angle data. Small-angle X-ray scattering data revealed the structure to be lamellar with repeat units in the range 3.48-3.90 nm, depending on the water content. Atomic force microscopy (AFM) allowed the film surface to be visually represented. It consists of characteristic elevations and depressions. The distance between the elevations ranges from 100 to 300 nm, and the elevations have a uniform height of about 3.4 nm, which confirms their lamellar structure. A detailed investigation of the viscoelastic properties was carried out using dynamic mechanical measurements. Master curves of the storage moduli of dry and wet samples were calculated.