Investigation on the aggregation behaviors of DDAB/NaDEHP catanionic vesicles in the absence and presence of a negatively charged polyelectrolyte

Abstract

The aggregation behaviors of the cationic and anionic (catanionic) surfactant vesicles formed by didodecyldimethylammonium bromide (DDAB)/sodium bis(2-ethylhexyl) phosphate (NaDEHP) in the absence and presence of a negatively charged polyelectrolyte are investigated. The amount of the charge on the vesicle can be tuned by controlling the DDAB/NaDEHP surfactant molar ratio. The charged vesicular dispersions made of DDAB/NaDEHP are mixed with a negatively charged polyelectrolyte, poly(4-styrenesulfonic acid-co-maleic acid) sodium (PSSAMA), to form complexes. Depending on the polyelectrolyte/vesicle charge ratio, complex flocculation or precipitation occurs. Characterization of the catanionic vesicles and the complexes are performed by transmission electron microscope (TEM), Cryo-TEM, dynamic light scattering (DLS), conductivity, turbidity, zeta potential, isothermal titration calorimetry (ITC) and small-angle X-ray scattering (SAXS) measurements.