Nonionic Fluorocarbon Surfactant Research Articles

Wettability of a Polymethylmethacrylate Surface by Fluorocarbon Surfactant Solutions

To clarify the adsorption behavior of fluorocarbon surfactants on PMMA surfaces, the contact angles of two nonionic fluorocarbon surfactants (FNS-1 and FNS-2) and an anionic fluorocarbon surfactant (FAS) on polymethylmethacrylate (PMMA) surface were determined using the sessile drop method. Moreover, the effects of molecular structures on the surface tension, adhesion tension, solid–liquid interfacial tension, and adhesion work of the three fluorocarbon surfactants were investigated. The results demonstrate that the adsorption amounts for three fluorocarbon surfactants at the air–water interface are 4~5 times higher than those at the PMMA–solution interface. The three fluorocarbon surfactants adsorb on the PMMA surface by polar groups before CMC and by hydrophobic chains after CMC. Before CMC, FNS-2 with the smallest molecular size owns the highest adsorption amount, while FAS with large-branched chains and electrostatic repulsion has the smallest adsorption amount. After CMC, the three fluorocarbon surfactants form aggregates at the PMMA-liquid interface. FAS possesses the smallest adsorption amount after CMC. Besides, FNS-1 possesses a higher adsorption amount than FNS-2 due to the longer fluorocarbon chain and the lower CMC value of FNS-1. The adsorption behaviors of nonionic and anionic fluorocarbon surfactants on the PMMA surface are different. FAS forms interfacial aggregates before CMC, which may be attributed to the electrostatic interaction between the anionic head of FAS and the PMMA surface.

In-situ deposition modification of hydrophilic polytetrafluoroethylene (PTFE) membranes using surfactants as anchoring points for long-term stability

Polytetrafluoroethylene (PTFE) membranes are renowned for their excellent thermal stability, resistance to strong acids and alkalis, and superior mechanical stability. However, its inherent strong hydrophobicity significantly limits its use in water treatment. In this study, a SiO2 coating was successfully deposited in-situ on the surface of PTFE membranes using a hydrolyzed solution of tetraethyl orthosilicate (TEOS) compounded with the commercial fluorinated polyoxyethylene ether surfactant FS-31 (C6F13CH2CH2O(CH2CH2O)nH). The modification mechanism involves using the low surface energy nonionic fluorocarbon surfactant FS-31, which interacts hydrophobically with the PTFE substrate, serving as an “anchor” point around which the TEOS hydrolyzes and condenses around the fibers and nodes of the PTFE membrane, forming a complete and stable chemical network structure. The results show that the initial water contact angle of the modified membrane dropped to 36.5°, and the water flux reached 537.9 L m−2 h−1. After being continuously immersed in strong acid (5 wt% HCl), strong alkali (4 wt% NaOH), and oxidizing agent (5 wt% NaClO) for one week, the membrane maintained excellent hydrophilicity and stability. This study proposes a mild and efficient modification method to prepare durable hydrophilic PTFE membranes, portending great potential for applications in harsh environments.

Surface properties, aggregation behavior and wettability of the mixed system of fluorocarbon cationic surfactant and hydrocarbon anionic surfactant in dilute solutions

Traditional perfluorooctane sulfonic acid (PFOS) fluorocarbon surfactants endangered human health and environment. Therefore, an environmentally friendly quaternary ammonium cationic fluorocarbon surfactant (PFAS-IEt) was synthesized, and surface activities, aggregation behavior, adsorption properties and wettability of PFAS-IEt/sodium n-octyl sulfate (SOS) mixtures in dilute solutions were systematically investigated. The results demonstrated that PFAS-IEt possessed excellent surface activity in aqueous solution. Surprisingly, its surface tension was only 15.33 mN/m and critical micelle concentration (CMC) was 0.002 mol/L. It could be used as a potential substitute for PFOS. In addition, PFAS-IEt had the good synergistic effect with SOS. The PTFE plate with low surface energy could be completely wetted by the binary compound solution at low concentration (0.04 mol/L) (contact angle was 0°), which was superior to the reported long chain quaternary ammonium non-ionic fluorocarbon surfactants (MN-2C9F19 and EN-2C9F19).

Fluorocarbon Surfactant‐Assisted Large‐Area Uniform and Water‐Resistant Perovskite Films for Efficient Photovoltaics

Formamidinium (FA)‐based lead triiodide perovskites are suitable light‐absorbing materials for solar cells due to their narrow bandgap, long‐range charge diffusion length, and excellent thermal stability. However, large‐area uniformity and phase purity are still challenging issues in the two‐step solution processed perovskite films because of the incomplete spreading/reacting of the organic amine salt solution. Herein, a novel multifunctional nonionic fluorocarbon surfactant (FS) is introduced to improve the crystallization of perovskites via the strategy of reducing the surface tension of the organic amine salt solution and facilitating the adequate binding of the organic amine salts with PbI2. Moreover, the FS additives effectively reduce residual PbI2; passivate the surface and interfacial defects of perovskites. The FS modified perovskite solar cells (PSCs) exhibit a champion power conversion efficiency (PCE) of 21.72% (0.16 cm2) with an enhanced stability, and the unencapsulated device maintains about 80% of the initial PCE even after 1000 h of storage. In addition, the larger PSCs with the active area of 1.00 cm2 deliver a peak PCE of 19.19%. Eventually, FS impedes moisture intrusion and effectively mitigates the decomposition of perovskite film. This work opens the way to explore large‐area PSCs with high performance and long‐term stability.

Evaluation of interfacial, micellar, and foaming properties of the solutions comprising fluorocarbon surfactant, cocamidopropyl betaine, and Gleditsia saponin as fire-extinguishing agents

The interfacial, micellar, and foam properties of unitary, binary, and ternary aqueous solutions containing a non-ionic fluorocarbon surfactant (FC-170C), an ionic hydrocarbon surfactant (CAB), and Gleditsia saponin (GS) were comprehensively investigated. FC-170C showed the highest surface activity and micellization ability, CAB and GS showed the strongest foaming ability and foam stability, respectively. For binary mixtures, the interaction in each pair of mixtures synergistically enhanced the ability of surface tension reduction, but had little synergistic effect on the efficiency of surface tension reduction. For the ternary mixtures, at an optimal formulation of 7.43 × 10-6 mol/L FC-170C, 5.26 × 10-3 mol/L CAB, and 1.60 × 10-4 mol/L GS, the values of γ, h0, R5min, and bubble size were 17.3 mN/m, 117 mm, 98%, and 115–116 μm, respectively. In particular, the required amount of fluorocarbon was reduced to 6.78 mg/kg, which is significantly<50 mg/kg limit set by international conventions for fire extinguishing agents.

Surface activity, wetting and foaming properties of amine-oxidized nonionic fluorocarbon surfactant and hydrocarbon anionic surfactants mixtures at low concentrations

Traditional perfluorooctanoic acid (PFOA) fluorocarbon surfactants are harmful to human health and environment. For this reason, a kind of low surface energy, environmentally friendly perfluorocarbon nonionic surfactant was prepared, and its surface property, aggregation behavior, foaming performance and wettability were systematically studied. The non-ionic fluorocarbon surfactant showed high surface activity in aqueous solution with the surface tension of 20.80 mN/m and the critical micelle concentration of 0.0043 mol/L. Besides, the amine-oxidized non-ionic fluorocarbon surfactant / SDS mixture had the good synergistic effect on the surface activity. It possessed good wettability at the low concentration (0.0022 mol/L), and its foaming performance and foam stability were improved with the increase of temperature. Also, the PTFE plate with low surface energy could be completely wetted by the compound solution. Moreover, the composite value of foam at 50℃ was as high as 54000 mL·s, which might be due to the superior surface activity and appropriate viscosity of the compound solution. Therefore, this study provided a potential process route for the development of high-performance foaming agents at high temperature.

Effect of xanthan gum and silica nanoparticles on improving foam properties of mixed solutions of short-chain fluorocarbon and hydrocarbon surfactants

The mixed dispersions of NPs, water-soluble polymer xanthan gum (XG), anionic hydrocarbon surfactant (sodium dodecyl sulfate [SDS]), and nonionic fluorocarbon surfactant (FS-50) were prepared by using an ultrasonic dispersion instrument to investigate the enhancement mechanism of NPs on the foam properties of surfactant. The molecular interactions, foamability, and foam stability of the mixed dispersions were comprehensively studied. Results suggested that the addition of XG resulted in an evident change of micelles from wormlike and spherical to threadlike in the solutions of FS-50/SDS. The foaming ability and foam stability of mixed dispersions were significantly affected by NPs and XG concentration. XG could better enhance foam stability of FS-50/SDS solutions compared with NPs, but lead to rapid decrease in foaming ability. NPs could enhance foaming ability and foam stability of FS-50/SDS solutions. Performance-enhanced foam, including foaming ability and foam stability, could be obtained by controlling the addition of XG and NP concentration.

A Comparative Experimental Study of Huff-n-Puff Gas Injection and Surfactant Treatment in Shale Gas-Condensate Cores

Experimental and simulation studies have thus far demonstrated that gas injection is an effective way of recovering condensate in shale gas-condensate reservoirs. It is economically feasible and relatively easier to be injected into the tight reservoir as compared to most of the other injection fluids. To the best of our knowledge, surfactant treatment has not been tested in shale cores for gas-condensate fluid systems. In this study, the experimental performances of huff-n-puff gas injection and surfactant treatment are compared in recovering condensate from shale cores. A nonionic fluorocarbon surfactant is screened for experiments based on dynamic contact angle measurements for suitable use in core flooding experiments. The principle of fluorocarbon surfactants is to alter the core from liquid wetting to favorably gas-wetting condition, thus reducing the average condensate saturation trapped in the core. First, an ideal experiment is used to set up two-phase gas and oil flow similar to a gas-condensate...

Binding of Procaine Hydrochloride to Hydrocarbon and Fluorocarbon Surfactants: The Role of Hydrophobicity

Aims: The interaction of procaine hydrochloride (PC.HCl) with sodium dodecyl sulfate (anionic hydrocarbon surfactant; SDS), Tween 20 (nonionic hydrocarbon surfactant), cetyltrimethyl ammonium bromide (cationic hydrocarbon surfactant; CTAB), lauryl sulphate betaine (amphoteric hydrocarbon surfactant; LSB) and Zonyl-FSN100 (non-ionic fluorocarbon surfactant; Zonyl FSN) has been aimed to study by UV-vis spectrophotometry. Methodology: Interactions with a fixed concentration of PC.HCl in the wide concentration range of Tween 20, Zonyl FSN, SDS, CTAB and LSB were studied spectrophotometrically at 298 K. Binding constants of PC.HCl to micelles was determined by using the Benesi-Hildebrand Equation. Results: Comparison of the binding constants (KB) showed that the most binding tendency of PC.HCl to micelles in case of Zonyl FSN. Due to the electrostatic repulsion between cationic CTAB and cationic PC.HCl the binding constant could not be calculated. The effect of Zonyl FSN on the binding of PC.HCl to hydrocarbon micelles has been also studied in the presence of fixed micelle concentration of Zonyl FSN. The binding tendency has been found to be related to the hydrophobicity of the medium. Conclusion: Interactions between different surfactants and amphiphilic drug PC.HCl showed that binding tendency of PC.HCl followed the order as; Zonyl FSN > Tween 20 > SDS > CTAB > LSB and presence of Zonyl FSN micelles increased incorporation of PC.HCl to all types of micelles.

Study on adsorption characteristic of novel nonionic fluorocarbon surfactant (4-hydroxyethyl ether) (pentadecafluoro-alkyl) amide at coal-water interface

Experimental investigations were carried out to examine the adsorption equilibrium, isotherm, kinetic behaviors of adsorption, and effect on adsorption-desorption of coal-bed methane (CBM) of the nonionic fluorocarbon surfactant (4-hydroxyethyl ether) (pentadecafluoro-alkyl) in the development process of CBM. The results show that the surfactant adsorption pattern is consistent with the Langmuir adsorption law for different rank coals, and the adsorption capacity is increasing from low-rank coal to high-rank coal. The surfactant adsorption process is spontaneous and endothermic, indicating that augmentation of temperature facilitates the adsorption of surfactant. The adsorption densities over electrolytes concentration on the surface of low-rank and medium-rank coal show the same trend; while for high-rank coal, it gives some details about the different trends. Adsorption densities decrease with pH value increasing of bulk solution for all coal samples. Adsorption behavior of surfactant is conducive to accelerating CBM desorption through wettability alteration of a coal surface.

Surfactivity of a Series of Nonionic Fluorocarbon Surfactant − Perfluorousnonenyl Polyethylene Glycol Ether

The surfactivity of nonionic fluorocarbon surfactants, polyethylene glycol perfluoro-nonyl monoether (C9F17-PEG-n) and diether (C9F17-PEG-n-C9F17), was systematically investigated, including the surface tensions (γ), critical micelle concentration (CMC), cloud point, foaming property and emulsifiability. The relation between their surface performance and their chemical structure of C9F17-PEG-n and C9F17-PEG-n-C9F17 were studied. The result showed that this series of fluorocarbon surfactant possessed high surface activity, the CMC &lt; 2.8 × 10-4 mol/L and the γCMC &lt; 25 mN/m. Compared to C9F17–PEG-n, C9F17-PEG-n-C9F17 have smaller minimum molecular area (Amin), greater saturated adsorption quantity (Γm), lower cloud point, poorer emulsifiability in toluene and greater foaming volume for their aqueous solutions. For either C9F17-PEG-n or C9F17-PEG-n-C9F17, with the increase of the PEG molecular weight (PEG-n), Γm declines, Amin increases and the emulsifiability in toluene becomes better, the CMC, γCMC and cloud point of their aqueous solutions increases, and their foaming volumes increase first and then decline, getting the maximum value at n=1000.

Understanding the structure of hydrophobic surfactants at the air/water interface from molecular level.

Understanding the behavior of fluorocarbon surfactants at the air/water interface is crucial for many applications, such as lubricants, paints, cosmetics, and fire-fighting foams. In this study, molecular dynamics (MD) simulations were employed to investigate the microscopic properties of non-ionic fluorocarbon surfactants at the air/water interface. Several properties, including the distribution of head groups, the distribution probability of the tilt angle between hydrophobic tails with respect to the xy plane, and the order parameter of surfactants, were computed to probe the structure of hydrophobic surfactants at the air/water interface. The effects of the monomer structure on interfacial phenomena of non-ionic surfactants were investigated as well. It is observed that the structure of fluorocarbon surfactants at the air/water interface is more ordered than that of hydrocarbons, which is dominated by the van der Waals interaction between surfactants and water molecules. However, replacing one or two CF2 with one or two CH2 group does not significantly influence the interfacial structure, suggesting that hydrocarbons may be promising alternatives to perfluorinated surfactants.

Investigation of micelle formation by N-(diethyleneglycol) perfluorooctane amide fluorocarbon surfactant as a foaming agent in aqueous solution

A novel nonionic fluorocarbon surfactant is synthesized and indicates excellent foaming performance and super surface activity.

Synthesis and Surface Activity of N-(2-Hydroxylpropyl) Perfluorooctane Amide Foaming Agent

Non-ionic fluorocarbon surfactant N-(2-hydroxypropyl) perfluorooctane amide was synthesized via the fattyacid method using perfluorooctanoic acid and isopropyl amine as precursors.The structures of products were characterized by infrared adsorption spectra(IR) and nuclear magnetic resonance spectroscopy(NMR).The bubbling potential,foam stability,salt resistance and surface tension of the samples were evaluated and compared with sodium dodecylsulfate(SDS).The results show that foam comprehensive exponent of the product is 1.6 times that of SDS.The foaminess is not obviously influenced by the concentration of inorganic ions.The surface tensions of the samples can be increased up to 9.275 mN/m.At lower concentration,the capability of reducing surface tension is better than that of SDS.The property of the products is strongly influenced by the type and quantity of hydrogen bonds,and the content of amides in the chain of the products.

Viscoelastic Wormlike Micelles in Mixed Nonionic Fluorocarbon Surfactants and Structural Transition Induced by Oils

Formation and rheological behavior of viscoelastic wormlike micelles in an aqueous solution of a mixed system of nonionic fluorocarbon surfactants, perfluoroalkyl sulfonamide ethoxylate, C8F17SO2N(C3H7)(CH2CH2O)nH (abbreviated as C8F17EOn, n=20 and 3), was studied. A partial ternary phase diagram of water/C8F17EO20/C8F17EO3 was constructed at 25 degrees C by visual inspection through crossed polarizers. In the water/surfactant binary system, C8F17EO20 forms an isotropic micellar solution over a wide concentration range (approximately 80 wt %). The micellar solution of the C8F17EO20 can solubilize a significant amount of C8F17EO3, and the solubility increases with increasing C8F17EO20 concentration. With successive addition of C8F17EO3 to the aqueous C8F17EO20 solution, viscosity increases rapidly, and a viscoelastic solution is formed. The viscosity of the viscous sample was approximately 5th order of magnitude of pure water. The viscoelastic solution follows the Maxwell model typical of wormlike micelles at low-frequency region. With further addition of C8F17EO3 the viscosity decreases, and phase separation occurs. Addition of perfluoropolyether oil, (C3F6O)nCOOH, to the viscoelastic solution decreases the viscosity monotonically until phase separation. On the other hand, when perfluorodecalin oil, C10F18, is added, viscosity first decreases and attains a limiting value before excess oil phase separates out. The viscosity decrease in water/surfactant/oil systems is possibly caused by the microstructural transition in the network structure. Small-angle X-ray scattering (SAXS) measurements were performed to complement the rheological data. It has been found that the C8F17EO3 induces one-dimensional growth to the C8F17EO20 micelles. On the other hand, when (C3F6O)nCOOH is added, wormlike-sphere type transition is more likely to occur.

Phase Behavior and Microstructures of Nonionic Fluorocarbon Surfactant in Aqueous Systems

The phase behavior and self-assembled structures of perfluoroalkyl sulfonamide ethoxylate, C8F17SO2N(C3H7)(CH2CH2O)20H (abbreviated as C8F 17EO20), a nonionic fluorocarbon surfactant in an aqueous system, has been investigated by the small-angle X-ray scattering (SAXS) technique. The C8F17EO20 forms micelles and different liquid crystal phases depending on the temperature and composition. The fluorocarbon micellar structure induced by temperature or composition change and added fluorocarbon cosurfactant has been systematically studied. The SAXS data were analyzed by the indirect Fourier transformation (IFT) and the generalized indirect Fourier transformation (GIFT) depending on the volume fraction of the surfactant and complemented by plausible model calculations. The C8F17EO20 forms spherical type micelles above critical micelle concentration (cmc) in the dilute region. The micelle tends to grow with temperature; however, the growth is not significant on changing temperature from 15-75 degrees C, which is attributed to the higher clouding temperature of the surfactant (>100 degrees C). On the other hand, the micellar structure (shape and size) is apparently unaffected by composition (1-25 wt %) at 25 degrees C. Nevertheless, addition of fluorocarbon cosurfactant of structure C8F17SO2N(C3H7)(CH2CH2O)H (abbreviated as C8F17EO1) to the semidilute solution of C8F17EO20 (25 wt %) favors micellar growth, which finally leads to the formation of viscoelastic wormlike micelles, as confirmed by rheometry and supported by SAXS. The onset sphere-to-wormlike transition in the structure of micelles in the C8F17EO20/water/C8F17EO1 system is due to the fact that the C8F17EO1 tends to go to the surfactant palisade layer so that the critical packing parameter increases due to a decrease in the effective cross-sectional area of the headgroup. As a result, spherical micelles grow into a cylinder, which after a certain concentration entangle to form a rigid network structure of wormlike micelles.

Interfacial Properties of Aqueous Nonionic Fluorocarbon Surfactant Solutions

The equilibrium, dynamic surface tensions, and surface dilatational elasticity of aqueous solutions of nonionic fluorocarbon surfactant are reported. The critical micellar concentration, CMC (0.023 mM) and equilibrium surface tension (24.6 m N . m−1) at CMC were measured by Wilhelmy plate method for aqueous solution of C8F17SO2N(C3H7)(C2H4O)nH (n=20), abbreviated as EF122A. The surface tension decay is slower for C8F17SO2N(C3H7)(C2H4O)nH (n=10) system, abbreviated as EF122B compared to the EF122A system over short time region, which indicates the slow transport of the surfactant molecules to the surface. The relaxation time for surface tension decay is estimated by fitting a series of exponentials to the dynamic surface tension data and it decreases with temperature for EF122A. Slow exchange of monomers between bulk and interface is reflected in the high elasticity value of the air‐liquid interface for EF122B compared with EF122A within measured frequency window (0.125–1.25 Hz).

Mesostructured fluorocarbon–silica hybrid materials with a low dielectric constant

The properties of a fluorocarbon–silica hybrid prepared by sol–gel hydrolytic polycondensation using a non-ionic fluorocarbon surfactant as a structure-directing agent are studied by small angle X-ray scattering, scanning electron microscopy, 29Si MAS-NMR, thermogravimetric analysis and dielectric relaxation. The obtained hybrid material consists mainly of micron-sized spherical particles with an internal two-dimensional hexagonal ( p6 mm) nanostructure. The material is thermally stable (with a high proportion of fully cross-linked silica) and shows a very low dielectric constant (about 2.15), which can be interesting from the point of view of applications.

Surface tension of HCl-based stimulation fluids at high temperatures

Surface tension of hydrochloric acid (HCl) solutions plays a key role in matrix stimulation of gas wells. A low surface tension is required to reduce the capillary forces that trap the aqueous phase in the formation. Accumulation of the aqueous phase near the well-bore area, known as water blockage, leads to a significant reduction in gas production. This work provides, for the first time, surface tension of acid-stimulating fluids at temperatures up to 120 °C, HCl concentrations up to 28 wt.%, and pressures up to 220 bar. A pendant drop apparatus specially designed for corrosive fluids was used to measure the surface tension between acid solutions and nitrogen. The effects of commonly used acid additives on the surface tension of HCl solutions were also studied in detail. These additives included corrosion inhibitors, acetic acid, formic acid, methanol, mutual solvent, a nonionic fluorocarbon surfactant, iron control chemicals, and hydrogen sulfide scavengers. In addition to surface tension values of HCl up to 28 wt.% HCl at temperatures up to 120 °C, experimental results indicated that several acid additives are capable of significantly lowering the surface tension of HCl solutions. The trends discussed in this study can be used to better design acid formulae used to stimulate deep gas wells.

An investigation of laser microprobe mass spectrometry (LAMMS) for polymer surface treatment and its inhomogeneity

Laser microprobe mass spectrometry was applied for the detection of inhomogeneity of the polycarbonate surface treated with silane coupling agent. Clear difference in spectrum patterns between the treatments with and without a non-ionic fluorocarbon surfactant was observed. The chemical bonds between silicon/zirconium and carbon have been confirmed to generate only in the presence of the surfactant which participates in homogenization of the surface.