(106d) Characterization Of Fluorinated And Hydrocarbon Mixed Cationic/anionic Surfactant Vesicles

Spontaneous vesicles formed by mixing single tailed anionic and cationic surfactants are potential microreactors and materials synthesis templates for catalysis, photochemistry, biochemistry, pharmaceutical, microelectronics, and petrochemical applications. Mixed cationic/anionic surfactant vesicles are easier to form than traditional kinetically stabilized vesicles. We examine the self-assembly behavior and bilayer properties of cationic/anionic vesicles formed by hydrocarbon/fluorocarbon and fluorocarbon/fluorocarbon surfactant mixtures, with a goal of exploiting the unique properties of fluorinated surfactants to tailor vesicle properties for their use as microreactors and templates. Fluorinated surfactants, whose tails are characterized as both lipophobic and hydrophobic, self assemble more readily than their hydrocarbon analogues and favor low curvature aggregates. We compare the properties of vesicles comprising fluorocarbon/fluorocarbon and hydrocarbon/fluorocarbon surfactant pairs to traditional hydrocarbon/hydrocarbon vesicles, as a function of surfactant chain length. Fluorinated sodium carboxylate salts (anionic surfactants), fluorinated pyridinium chlorides (cationic surfactants) and their hydrocarbon analogues are used to produce mixed cationic/anionic surfactant vesicles. Vesicle size is characterized by dynamic light scattering and confirmed by transmission electron microscopy. The effect of fluorocarbon surfactant incorporation on the gel-liquid phase transition is examined using differential scanning calorimetry and fluorescence anisotropy. The formation of fluorocarbon/fluorocarbon vesicles from cationic/anionic surfactant mixtures is not well investigated, and the region of vesicle formation is further explored as a function of chain length and asymmetry of the surfactant pairs. The potential to template hollow silica spheres from fluorocarbon/fluorocarbon cationic/anionic surfactant vesicles is demonstrated.