Mixtures Of Fluorocarbon Surfactants Research Articles

Adjustable surface activity and wetting ability of anionic hydrocarbon and nonionic short-chain fluorocarbon surfactant mixtures: Effects of Li+ and Mg2+

Achieving wide variation ranges and various adjusting modes of the performances for surfactant mixtures is still a significant challenge which limits the extensive application of surfactant mixtures. Herein, we reported the physicochemical properties and performances of hydrocarbon/fluorocarbon surfactant mixtures constituted with an anionic hydrocarbon surfactant, sodium dodecyl sulfate (SDS), and a tri-block nonionic short-chain fluorocarbon surfactant (F9EG13F9). Meanwhile, the effects of Li+ and Mg2+ on them were investigated. The surface tension and contact angle measurements were adopted to reflect the surface activity and wetting ability of SDS/F9EG13F9 mixtures. The data showed that the surface tensions at the critical micelle concentrations and the contact angles on polytetrafluoroethylene film of these surfactant mixtures are 33.5–21.4 mN/m and 118.0–58.7°, respectively, which indicates that their surface activity and wetting ability possess wide variation ranges. Furthermore, the micellization, adsorption and thermodynamics behaviors of mixed surfactants were also analyzed using a series of theoretical parameters based on the regular solution theory, Clint’s model, Maeda’s model, etc. The results approved that Li+ and Mg2+ immensely reduce the electrostatic repulsion effect of SDS and increase the adsorption of SDS at phase interfaces to enhance mixed monolayer packing, in which the effect of Mg2+ is stronger than that of Li+. Thus, precisely adjustable surface activity and wetting ability can be realized by changing the molar ratio and adding the different cations, which enables SDS/F9EG13F9 mixtures to possess tunable performances to meet various practical application requirements.

Strong synergistic effect of cationic hydrocarbon surfactant and novel nonionic tri-block short-chain fluorocarbon surfactant mixtures on surface activity, wettability and solubilization

Mixing hydrocarbon surfactants with fluorocarbon surfactants is still an important strategy to improve the economic benefits and performances of fluorocarbon surfactants and expand their range of application. Herein, we prepared a novel kind of hydrocarbon-fluorocarbon surfactant mixtures via mixing a cationic surfactant, cetyltrimethylammonium bromide (CTAB), with a tri-block nonionic short-chain fluorocarbon surfactant (F9EG13F9) in aqueous solution. The results showed that adding a small CTAB amount to F9EG13F9 (the molar fraction of CTAB in the mixture (x1) was 0.2) could greatly reduce its critical micelle concentrations (cmc) from 0.408 mmol/L to 0.191 mmol/L. At this x1, the contact angle of the mixture was the minimum (57.7 °) at 100 s on polytetrafluoroethylene film, which was even lower than that of F9EG13F9. Besides, CTAB/F9EG13F9 mixtures possessed better colloidal stability and solubilization ability toward hydrophobic dye (Sudan І) than F9EG13F9. The outstanding performances of binary surfactant mixtures benefited from the non-ideal mixing and strong synergistic effect evidence that CTAB/F9EG13F9 surfactant mixtures could be used in practical applications instead of individual F9EG13F9, thereby reducing the used cost of F9EG13F9.Graphical abstract

A simple strategy to improve surface activity and wettability of anionic hydrocarbon and tri-block nonionic short-chain fluorocarbon surfactant mixtures

To address the problem that the surface activity of reported hydrocarbon-fluorocarbon (CH-CF) surfactant mixtures was usually difficult to reach the level of corresponding CF surfactant, we reported a simple strategy that is utilizing the electrostatic screen effect of inorganic cation (Na+) on anionic surfactant to control the interfacial arrangement of anionic-nonionic mixed surfactants and improve the surface activity and wettability of novel CH-CF surfactant mixtures constituted with an anionic surfactant, sodium dodecylbenzene sulfonate (SDBS), and a tri-block nonionic short-chain fluorocarbon surfactant (F9EG13F9). The results showed that at 0.25 mol/L NaCl, the surface activity of surfactant mixture was on a par with that of individual F9EG13F9 (21.4 mN/m) when the molar fraction of SDBS in the mixture (x1) was 0.6, and its cmc value (0.154 mmol/L) was less than individual F9EG13F9 (0.408 mmol/L). At this x1, the contact angle had the minimum value (70.2°) on polytetrafluoroethylene film. The findings mentioned above probe that the SDBS/F9EG13F9 surfactant mixture with a specific proportion is a potential alternative for individual F9EG13F9 at appropriate NaCl content, which can effectively reduce the used cost of F9EG13F9 without reducing its surface activity and wettability.

Effect of Hydrophobic Chains on Solubilization of Hydrocarbon and Fluorocarbon Surfactant Mixtures in Aqueous Solution.

We investigated the solubilization behavior of the hydrocarbon surfactant lithium dodecyl sulfate (LiDS) and the fluorocarbon surfactant lithium 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluoro-1-octanesulfonate (LiFOS) in an aqueous solution to determine the controlled release mechanism of solubilizate. The LiDS system solubilized Sudan III, a hydrocarbon compound, whereas the LiFOS system did not, because of the immiscibility of the hydrocarbon and fluorocarbon compounds. The solubilization ability of the LiDS and LiFOS mixtures gradually decreased with increasing LiFOS bulk composition because the micelles mainly composed of LiDS transformed into micelles mainly composed of LiFOS. Furthermore, Sudan III solubilized in the aqueous LiDS was deposited when an aqueous LiFOS was added. The difference in the solubilization behavior between LiDS and LiFOS enabled the controlled release of the solubilizate.

Study of the influence of the binary mixtures of fluorocarbon surfactants on the surface tension of water

Influence of the binary mixtures of fluorocarbon surfactants Zonyl FSO-100 (FSO100) and Zonyl FSN-100 (FSN100) on the surface tension of the water was studied. The effectiveness of adsorption process of the surfactant at the water-air interface was calculated from the obtained values of the surface tension of studied mixtures. Also the maximum surface area per molecule of surfactant in the interfacial area and the free energy at the water-air interface were determined. Moreover, the existence of synergetizm or antagonism effect, which reduces the surface tension of the water was examined. On the basis of the Rosen's model parameter the values of intermolecular interactions in the mixed monolayer adsorption were calculated.

Effect of two hydrocarbon and one fluorocarbon surfactant mixtures on the surface tension and wettability of polymers

The advancing contact angle of water, formamide and diiodomethane on polytetrafluoroethylene (PTFE) and polymethyl methacrylate (PMMA) surfaces covered with the film of ternary mixtures of surfactants including p-(1,1,3,3-tetramethylbutyl) phenoxypoly(ethyleneglycols), Triton X-100 (TX100) and Triton X-165 (TX165) and the fluorocarbon surfactants, Zonyl FSN-100 (FSN100) or Zonyl FSO-100 (FSO100) was measured. The obtained results were used for the surface tension of PTFE and PMMA covered with this film determination from the Young equation on the basis of van Oss et al. and Neumann et al. approaches to the interfacial tension. The surface tension of PTFE and PMMA was also determined using the Neumann et al. equation and the contact angle values for the aqueous solutions of the above mentioned ternary surfactants mixtures which were taken from the literature. As follows from our calculations mainly the presence of the fluorocarbon surfactant in the mixture considerably changes the surface properties of PTFE and PMMA causing that in contrast to hydrocarbon surfactants and their mixtures there is no linear dependence between adhesion and surface tension in the whole range of concentration of the ternary mixtures of surfactants including the fluorocarbon one. The behavior of fluorocarbon surfactants at the polymer–air and polymer–water interfaces is quite different from those of hydrocarbons. In the case of fluorocarbon surfactants not only adsorption but also sorption can occur on the polymer surface.

Phase behavior, rheological properties, and vesicles of alkyldimethylamine oxide and fluorinated acidic surfactant mixtures

Weakly basic alkyldimethylamine oxide (CnDMAO, n = 12, 14, and 16) molecules can be protonated to form a cationic surfactant, CnDMAOH+, by an acidic fluorocarbon surfactant, 8-2-fluorotelomer unsaturated acid (C7F15CFCHCOOH), to produce the salt-free cationic and anionic (catanionic) surfactant mixtures in aqueous solution. These comparative studies on phase behavior and rheological properties of these salt-free catanionic hydrocarbon–fluorocarbon surfactant mixtures in detail clearly indicate the existence of a birefringent Lα-phase for C12DMAO/C7F15CFCHCOOH and C14DMAO/C7F15CFCHCOOH systems at 25.0 ± 0.1 °C. However, the birefringent Lα-phase of C16DMAO/C7F15CFCHCOOH system exist at 60.0 ± 0.1 °C. The birefringent Lα-phase which consists of uni- and multilamellar vesicles, and oligovesicular vesicles is independent of the hydrocarbon chain of CnDMAO at controlled temperatures. The vesicles were demonstrated by cryo-transmission electron microscopy (cryo-TEM) and negative-staining TEM images, in which pliability of the bilayer membranes decreases with the increasing length of hydrogenated chains of hydrocarbon surfactants. The formation of the salt-free catanionic Lα-phase consisting of vesicles could be induced by the strong electrostatic interaction between the cationic hydrocarbon C14DMAOH+ and the anionic fluorocarbon C7F15CFCHCOO−, C14DMAOH+ is produced through acid–base reaction of C14DMAO and C7F15CFCHCOOH. The rheological properties of micelles and vesicles in the three mixture systems were measured, which provided much more information about the hydro- and fluorocarbon surfactant mixtures. The size distribution and structural transition of these similar systems but having different length chains of hydrocarbon surfactants were studied by dynamic light scattering (DLS) and 1H and 19F NMR spectroscopy.