Synthesis and applications of surfactants containing fluorine

Syntheses and solution properties of novel fluorinated surfactants with branched tail, especially on anionic surfactants having two polyfluoroalkyl chains and on anionic surfactants having different hydrophobic chains (hybrid surfactants), are reviewed. For example, when the fluorocarbon chain length in the surfactants possessing two polyfluoroalkyl chains increases, the Krafft points and the area of surfactant molecule at the air-water interface increases, the critical micelle concentration decreases, but the degrees of ionic dissociation of micelle are almost the same. Moreover, the flocculation and redispersion abilities of these surfactants for dispersed magnetic particles in water are enhanced by an increase in the chain length. The hybrid surfactants are found to have the ability to considerably lower surface tension, and they can emulsify a ternary-component system of hydrocarbon/water/perfluoropolyether oil. Furthermore, some of the hybrid surfactants show anomalous solution properties and thermoresponsive viscoelasticity due to the assembly structure changes with increasing its concentration.