Fluorocarbon hybrid surfactants characterization of admicelles and its solubilization

Admicelle formation of the fluorocarbon hybrid surfactant 1-oxo-1-[4-(fluoroalkyl)phenyl]-2-alkanesulfonate (FCm-HCn) on the aluminum oxide particle surface has been studied by the adsorption isotherm, zeta-potential of the particle surface, degree of counterion dissociation, contact angle, and pyrene fluorescence probe measurement. Solution properties of FCm-HCn have been compared with a dialkyl hydrocarbon surfactant, sodium 1-4-alkylphenyl-1-oxo-2-alkanesulfonate (HCm-HCn). Adsorption isotherm study and zeta-potential measurement indicate that the fluorocarbon hybrid surfactant can adsorb on the aluminum oxide surface at lower concentrations than the hydrocarbon surfactant. Furthermore, the total amount of surfactant adsorbed on the aluminum oxide surface is higher than that of the hydrocarbon surfactant. A pyrene fluorescence probe study shows that pyrene molecules are solubilized near the hydrocarbon chain of the surfactant molecules, indicating that the hydrocarbon domain exists in the fluorocarbon hybrid surfactant admicelle. No pyrene excimer formation is observed in the hybrid surfactant admicelle but in the hydrocarbon surfactant, implying the hybrid surfactant molecules are packed tightly in the admicelle. In addition, the admicelle of the hybrid surfactant is capable of solubilizing both 2-naphthol and 1-trifluoromethyl-2-naphthol and the total amount of solubilized solute increases with increasing surfactant concentration.