Synergistic Properties of a Mixed Micelle System Consisting of a Nonionic Fluorinated Surfactant and a Cationic Surfactant

The physicochemical properties of aqueous surfactant mixtures containing a nonionic fluorosurfactant (undecafluoro-n-pentyldecaoxyethylene ether (C5F11EO10)) and various amounts of a cationic surfactant (decyltrimethylammonium bromide (DeTAB)) were determined by surface tension and conductivity measurements. All values of the critical micelle concentrations of the mixtures turn out to be smaller than those of both pure surfactants revealing the presence of a significant synergy for all DeTAB proportions in the mixed system. The analysis of the experimental data was performed on the basis of three different well established thermodynamic models of mixed micelle formation to determine several relevant parameters, especially the micelle composition, the interaction parameters, and the free energy of micelle formation. The results indicate that the dominant interactions between DeTAB and C5F11EO10 molecules are attractive. The main reason for this behavior could be attributed to the complexation between the polyoxyethylene chain of C5F11EO10 and the quaternary ammonium group of DeTAB giving rise to stable structures.

Influence of the Hydro/Fluorocarbon Chain Length on CMC and HLB of Surface-Active Nonionic Surfactants Containing Polyethylene Glycol Groups

Series of cyclic polyethylene glycol succinates based surfactants bearing a hydro- or fluorocarbon group was synthesized and characterized. Evaluation of the surface-active properties of the obtained compounds reveals, (i) the surface tension decreases gradually when is the length of the lipophilic chain increased (ii) the critical micelle concentration (CMC) increases with the number of ethylene oxide unit present in the polar head and (iii) surface tension follows the increasing pattern of hydrophilic-lipophilic balance (HLB) number.

Syntheses of Tartaric Acid-Based Hybrid Gemini Surfactants Containing Fluorocarbon and Hydrocarbon Chains

Tartaric acid-based symmetric and hybrid gemini surfactants having dodecyloxy (C12H25O-) and tridecafluoro nonyloxy groups (C6F13(CH2)3O-) as hydrophobic groups were synthesized, and their surface properties were studied by surface tension (γ)-concentration and surface pressure-area (π-A) measurements. All geminis showed superior surfactant properties to 1+1 type surfactant. Especially, hybrid gemini showed high efficiency of lowering the surface tension comparable to that of bis(C6F13(CH2)3O) gemini. Further, hybrid gemini showed an unusual existence of two breakpoints at γ = ∼25 and 18 mN m−1. In the π-A measurements, regardless of symmetric or hybrid structures, geminis having fluoroalkyl group formed only liquid condensed monolayers while the bis(dodecyloxy) gemini formed solid monolayer. Molecular occupied areas of hybrid gemini were subequal to the mean of those of symmetric geminis.