Fluorocarbon Surfactants Research Articles

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.

Design and evaluation of an innovative composite silicate-based surface treatment agent of concrete

Silicate-based surface treatment agent is a sustainable material to provide a sealing coat on the surface of Portland cement concrete to improve its hardness, impermeability, chemical durability, and abrasion resistance. A type of composite surface treatment agent of concrete is introduced in the paper, using potassium silicate and lithium silicate as main agents and different contents of lithium sulfate, urea, triethanolamine, organosilicon polyether surfactant, and fluorocarbon surfactant as additives. An orthogonal test was conducted to evaluate the effects of different proportions of the two main agents and five additives. The gelation time and viscosity of the agent and the rebound value and penetration depth of the tested concrete samples were tested to evaluate the performance of the designed composite material. The results showed that the two main agents had significant influences on the viscosity, while potassium silicate had the greatest influence on the rebound value. For penetration depth, urea, triethanolamine, organosilicon polyether nonionic surfactants, and fluorocarbon surfactants all had significant effects. The proper ingredients were selected based on the test results, and the optimum proportion of the designed surface treatment agent was determined based on variance analysis of the test results. Two representative commercial inorganic surface treatment agents were selected to compare with the optimum proportion of the designed material, and the effects of the material on the microstructures of the concrete specimens were analyzed by scanning electron microscope (SEM). The mechanism is that Calcium Silicate Hydrate (CSH) gel and ettringite generated can effectively improve surface properties of concrete. The results showed that the optimum proportion of the designed material can effectively block micropores in the surface layer, thus significantly decreasing the concrete porosity, which is conducive to the rapid improvement of concrete strength and compactness.

Discovery of 35 novel classes of per- and polyfluoroalkyl substances in representative commercial fluorinated products in China

Per- and polyfluoroalkyl substances (PFAS) have received increasing scientific and regulatory attention due to their global distribution and health hazards. However, little is known about the PFAS composition of fluorinated products commercially available in China. In this study, a sensitive and robust analytical method was proposed for the comprehensive characterization of PFAS in aqueous film-forming foam and fluorocarbon surfactants in the domestic market based on liquid chromatography-high resolution mass spectrometry in full scan acquisition mode followed by parallel reaction monitoring mode. Consequently, a total of 102 PFAS from 59 classes were elucidated, of which 35 classes are reported for the first time, including 27 classes of anionic, seven classes of zwitterionic, and one class of cationic PFAS. The anionic-type products are mainly C6 fluorotelomerization-based (FT-based) PFAS. Perfluorooctanoic acid and perfluorooctane sulfonate are negligible, while some known electrochemical fluorination-based long-chain precursors in zwitterionic products are worthy of concern because of their high abundance and potential degradation. New precursors detected in zwitterionic products are FT-based PFAS, for example, 6:2 FTSAPr-AHOE and 6:2 FTSAPr-diMeAmPrC. The structural elucidation of PFAS in commercial products facilitates a better assessment of human exposure and environmental release.

The effect of short-chain fluorocarbon and electrolyte on simultaneous dedusting and explosion prevention performance when applied to coal particle with high oil-content

The fully mechanized mining faces in underground oil-rich coal mines are exposed to the serious dust pollution and the high risk of dust explosion. Traditional materials cannot effectively realize the removal and inerting of coal particles with high oil content. Thus, this paper innovated new materials to eliminate the occupational disasters and explosion accident in underground coal mines by achieving simultaneous dedusting and explosion prevention of coal particles with high oil content. Compare with traditional materials, the presence of short-chain fluorocarbon surfactants and electrolytes achieved 76.30–84.92% improvement on dedusting rate, a maximum 22 times improvement on MIE, 4.20–8.90% improvement on MIT, and 50% improvement of MEC. Mechanism analysis revealed the better performance is attributed to the optimized wetting and agglomerating behaviour. Kinetic analysis showed that the new materials reduced the heat release and inhibit combustion process. The NaCl outperforms NaHCO3 in achieving better dedusting and explosion suppression performance in most cases for its higher TSI and more efficient explosion prevention mechanisms. Studies also demonstrated that the oil content could moderate the dedusting and explosion prevention performance due to the reduction of static liquid bridge force in terms of the increased proportion of saturated hydrocarbons and aromatic hydrocarbons, the reduced concentration of polar functional group, and the corresponding increased contact angle “θ”. The Findings of this paper provide an efficient and environmental-friendly choice for ensuring occupational health and safe production in underground oil-rich coal mines by achieving simultaneous dedusting and explosion prevention. It will also guide the innovation and development of multiple protective materials for coal mine safety protection.

Robust, anti-icing, and anti-fouling superhydrophobic coatings enabled by water-based coating solution

Superhydrophobic coatings have a wide range of applications in all areas of our lives, however, poor mechanical robustness limits their practical use. The use of organic solvents to prepare coatings can pose safety and environment pollution problems, also increase the cost of production. Water-based coating solution is used to prepare superhydrophobic coatings, which are safe and easy to scale. Thus, we demonstrate that silica nanoparticles, fluorinated alkyl silanes (FAS), fluorocarbon surfactants (FS-3100), and water can form stable system for preparation of superhydrophobic coatings on soft and hard substrates. After coating treatment, the superhydrophobic coatings exhibit excellent chemical stability (resistant to acid, alkali, salt, and ultraviolet radiation) and good mechanical robustness due to superhydrophobicity and crosslinking effects of FAS and FS-3100. Furthermore, the superhydrophobic coatings can delay water freezing time and poses superior anti-icing performance. This simple water-based coating solution may provide a new way of thinking for the later development of new coating technologies that are economical for all applications.

On the mechanism of enhanced foam stability by combining carboxylated cellulose nanofiber with hydrocarbon and fluorocarbon surfactants

The effect of carboxylated cellulose nanofiber (CCNF) on the firefighting foam stability and stabilization mechanism is investigated. The results show that equilibrium surface tension of CTAB/FC1157 solution decreases when CCNF concentration increases to 0.5 wt%, while CCNF has little effect on that of SDS/FC1157 solution. Besides, when CCNF concentration increases to 1.0 wt%, the foam initial drainage of SDS/FC1157 solution is delayed for about 3 min. Increasing CCNF concentration can slow down foam coarsening process and liquid drainage process of SDS/FC1157 and CTAB/FC1157 solutions, improving the foam stability. The foam stability enhancement of CTAB/FC1157-CCNF solution is due to the formation of bulk aggregates and the increase of viscosity. However, the foam stability enhancement of SDS/FC1157-CCNF solution may be caused by the increase of viscosity. CCNF significantly reduces the foaming ability of CTAB/FC1157 solution when CCNF concentration is >0.5 wt%. Nevertheless, the foaming ability of SDS/FC1157 solution decreases significantly when CCNF concentration reaches 3.0 wt%, and its foaming ability remains higher than CTAB/FC1157 solution. The foaming ability of SDS/FC1157-CCNF solution is mainly dominated by viscosity, while that of CTAB/FC1157-CCNF solution is dominated by viscosity and adsorption kinetics. Adding CCNF is expected to enhance the stability of firefighting foam and increase the efficiency of extinguishing fire.

Microencapsulation of Lead-Halide Perovskites in an Oil-in-Fluorine Emulsion for Cell Imaging.

The superior optical properties of lead-halide perovskites (LHPs) inspired significant research in cell imaging applications; many encapsulating processes have improved perovskite stabilities with comparable biosafety. Herein, facile solvent evaporation encapsulation based on an oil-in-fluorine emulsion for aqueous-stable and extremely nontoxic LHP microcapsules is described. Perfluorooctane dispersed the emulsifier fluorocarbon surfactant to form a continuous fluorine phase, while LHPs and polymethylmethacrylate (PMMA) were dispersed in 1,2-dichloroethane, then emulsified in the fluorine phase to form an oil-in-fluorine emulsion. CsPbBr3 microcapsules with a dense PMMA shell that protect fragile CsPbBr3 from the external environment and inhibit lead ion release were obtained after solvent evaporation. The CsPbBr3 microcapsules not only retained 91% of fluorescence intensity after exposure to water for 30 d but also possess extremely low cytotoxicity for MCF-7 cells. After exposure to 2 mg/mL of CsPbBr3 microcapsules for 48 h, the cell viability remained >90%. The intracellular uptake of CsPbBr3 microcapsules indicates its potential use in cell imaging.

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.

An antifouling and acid resistant loose NF membrane via synergic modification of PVP and PEI on PTFE substrate

Polytetrafluoroethylene (PTFE) with good resistance can be used under extreme conditions, however, its surface hydrophobicity greatly limits its wide application in water treatment field. In this work, the hydrophobic PTFE microfiltration (MF) membrane was innovatively modified into a hydrophilic loose nanofiltration (NF) via synergic effect of the deposited polyethyleneimine (PEI) and poly(vinylpyrrolidone) (PVP) with assistance of fluorocarbon surfactant (FCS), and then crosslinked by glutaraldehyde (GA). The surface morphology, porosity and aperture size of the obtained cPEI-PVP-FCS/PTFE (cPPF) membrane were characterized in detail. The resultant membrane showed good dye desalination performance with high Evans blue rejection of 98.5%, NaCl rejection of 13.4%, along with permeance of 192.1 L m−2 h−1·MPa−1. In addition, the membrane showed long-term stability and good acid resistance.

Synthesis of Carboxyl Modified Polyether Polysiloxane Surfactant for the Biodegradable Foam Fire Extinguishing Agents.

It is necessary to develop novel and efficient alternatives to fluorocarbon surfactant and prepare fluorine-free environmentally-friendly fire extinguishing agent. The carboxyl modified polyether polysiloxane surfactant (CMPS) with high surface activity was synthesized via the esterification reaction using hydroxyl-containing polyether modified polysiloxane (HPMS) and maleic anhydride (MA) as raw materials. The process conditions of the esterification reaction were optimized by orthogonal tests, and the optimum process parameters were determined as follows: reaction temperature of 85 °C, reaction time of 4.5 h, isopropyl alcohol content of 20% and the molar ratio of HPMS/MA of 1/1. The chemical structure, surface activity, aggregation behavior, foam properties, wetting properties and electron distribution were systematically investigated. It was found that the carboxyl group was successfully grafted into silicone molecule, and the conjugated system was formed, which changed the interaction force between the molecules and would affect the surface activity of the aqueous solution. The CMPS exhibited excellent surface activity and could effectively reduce the water's surface tension to 18.46 mN/m. The CMPS formed spherical aggregates in aqueous solution, and the contact angle value of CMPS is 15.56°, illustrating that CMPS had excellent hydrophilicity and wetting performance. The CMPS can enhance the foam property and has good stability. The electron distribution results indicate that the introduced carboxyl groups are more inclined towards the negative charge band, which would be conducive to weak the interaction between molecules and improve the surface activity of the solution. Consequently, new foam fire extinguishing agents were prepared by using CMPS as a key component and they exhibited excellent fire-fighting performance. The prepared CMPS would be the optimal alternative to fluorocarbon surfactant and could be applied in foam extinguishing agents.

Comparative study on foaming and foam stability of multiple mixed systems of fluorocarbon, hydrocarbon, and amino acid surfactants

AbstractThis study focuses on the effect of amino acid surfactant (sodium lauroyl glutamate [SLG]) on foam properties of a mixture of fluorocarbon (FS‐50) and hydrocarbon (APG0810) surfactants. The molecular interactions, foamability, and foam stability of the surfactant solutions are systematically studied. The results show that SLG has stronger ability to lower surface tension of water compared to APG0810, but worse that than FS‐50, and to adsorb onto gas/liquid interface in mixed solutions with FS‐50 compared to APG0810. The addition of SLG increased foamability of APG0810/FS‐50 mixed solution, and decelerated foam drainage and coarsening of individual APG0810, individual FS‐50, and mixture of APG0810/FS‐50 solutions. The mixture of SLG/FS‐50 exhibited the higher foamability and foam stability than the frequently used critical component of the new developed AFFF, the mixture of APG0810/FS‐50. This study can provide guidance for the scientific application of amino acid surfactants in the development of environmentally friendly firefighting foams.

Preliminary exploration of a novel high-performance air entraining agent based on sodium dodecyl sulfate added self-made fluorocarbon surfactant

Sodium dodecyl sulfate (SDS), an air entraining agent (AEA), is used to improve the frost resistance of concrete, but the effectiveness of SDS is urgent to be improved because it is easily weakened by many factors. In this work, a novel high-performance AEA (HPAEA) was prepared by compounding sodium dodecyl sulfate (SDS) with the self-made fluorocarbon surfactant (S-FC). The performance of HPAEA in cement paste solution and in mortar were evaluated and the improvement mechanism was explored. The results of foamability and foam stability in cement paste solution, air content and air-void parameters in cement mortar showed that S-FC could greatly promote the foam properties of SDS and optimize the air-void structure in entrained mortar. When the concentration of S-FC reached 0.2 wt%, foamability, foam stability, fresh air content of HPAEA was 2.9 times, 16.5 times, and 1.6 times higher than that of SDS, respectively. The air-void spacing factor in hardened mortar was reduced by more than 50%. The improvement mechanism of the effectiveness of HPAEA was revealed by the lower surface tension and better comprehensive property of the bubble liquid film, because there was synergistic effect between SDS and S-FC. It was concluded that the novel HPAEA obtained by compounding SDS with S-FC had a potential to significantly improve the frost resistance of concrete.

Comparative study on foaming and foam stability of multiple mixed systems of fluorocarbon, hydrocarbon, and amino acid surfactants

Comparative study on foaming and foam stability of multiple mixed systems of fluorocarbon, hydrocarbon, and amino acid surfactants

Synthesis and properties of novel betaine fluorocarbon surfactants

Synthesis and properties of novel betaine fluorocarbon surfactants

Microwave absorbing properties of electrodeposited mixed flake-like and dendritic-like FexNi1−x alloy particles

Electrodeposition as a simple and effective method is widely used in the production of metallic materials. In this paper, we prepared mixed flake-like and dendritic-like FexNi1−x (x = 0.5, 0.33, 0.25, 0.2) alloy particles by electrodeposition in constant current mode using fluorocarbon surfactant (FS) and emulsifier OP-10 (OP-10) as the surfactants. The crystal structure, morphology and electromagnetic properties of FexNi1−x were characterized by X-ray diffraction, scanning electron microscopy, vibrating sample magnetometry, and vector network analysis. The effects of different values of x on the morphologies and structures of the FexNi1−x particles were investigated. The growth mechanism of FexNi1−x from hemispherical to a mixture of dendritic and flaky structures was discovered. The electromagnetic parameters and microwave absorbing properties of the composites of the FexNi1−x were studied in 2–18 GHz. All FexNi1−x alloy particles have good absorbing properties, among which the prepared Fe0.25Ni0.75 exhibits the best microwave absorption properties, whose minimum reflection loss (RLmin) reaches − 68.64 dB at 5.76 GHz when the thickness is 3.4 mm, and the maximum effective bandwidth (RL<−10 dB) is 4.56 GHz when the thickness is 1.5 mm. The excellent microwave absorbing property of Fe0.25Ni0.75 is from its excellent impedance matching characteristics.

Airborne high oil-content coal particles suppression via the electrolyte accelerated application of hydrocarbon and short-chain fluorocarbon surfactants

This paper studied the wetting and agglomerating behaviour of high oil-content coal particles, during the electrolyte accelerated synergistic application of hydrocarbon and short-chain fluorocarbon surfactants. The addition of short-chain fluorocarbon contributed 42.91 % ∼ 71.71 % reduction on surface tension and 51.08 % to 59.54 % reduction on immersing time. The short-chain fluorocarbon surfactant also achieves 29.17 % ∼ 258.93 % improvement on TSI and 48 % ∼ 104 % improvement on dust suppression rate. The presence of electrolytes further enhanced those performances by contributing an extra 7.95 % ∼ 18.41 % reduction on surface tension, 54.99 % ∼ 75.73 % reduction on immersing time for oil-rich and oil-high coal particles, 1.95 ∼ 19.16 times higher TSI and 23.35 % ∼ 31.85 % increasement on dedusting rate. The agglomerating behaviour is more accurate in predicting the dedusting rate. The increased oil content led to significant reduction on static and total liquid bridge force, and finally resulted in deteriorated dedusting rate due to the diminished wetting and agglomerating performance.

Study on the effect of nanoparticles combined with silicone surfactant and cationic surfactant on foam and fire extinguishing performance.

Aqueous film-forming foam (AFFF) in firefighting foam can effectively extinguish oil fire. However, AFFF will be phased out due to the presence of persistent organic pollutants such as perfluorooctane sulfonates. It is necessary to explore environment-friendly foam extinguishing agent. Silicone surfactant is a kind of environmentally friendly surfactants with high surface activity, which can be used as a substitute for fluorocarbon surfactant. In this study, silicone surfactant and cationic surfactant were combined to adsorb nanosilica particles to form a multiphase system. The foaming property and foam stability of the multiphase system were tested by stirring method. The foam suppression effect on fuel vapor, fire extinguishing, and burn-back performance was tested by self-designed foam suppression device and foam generating device of porous glass with recyclable liquid supply. The experimental results show that foam stability is enhanced and the foaming property is slightly decreased after the addition of nanoparticles. When the component of three-phase foam reaches the optimum, its suppression effect on fuel vapor is better than that of two-phase foam. The results of fire extinguishing and burn-back performance test showed that the fire extinguishing effect of three-phase foam was slightly worse than that of AFFF, but it has extremely strong burn-back performance.

Suspect screening and nontargeted analysis of per- and polyfluoroalkyl substances in representative fluorocarbon surfactants, aqueous film-forming foams, and impacted water in China

Massive usage of aqueous film-forming foams (AFFF) containing fluorocarbon surfactants (FS) is one of the major sources of per- and polyfluoroalkyl substances (PFAS) contamination, which poses negative environmental and health effects. However, there is a critical knowledge gap regarding PFAS chemical compositions in high consumption FS products which were used in AFFFs on the Chinese market and in water impacted by such products. This study firstly applied a comprehensive suspect screening and nontargeted analysis (NTA) workflow to investigate the main ionic and neutral PFAS in FS products from the largest Chinese vendor and compared with two international brands to unveil the PFAS used in AFFF. Overall, 24 classes of PFAS, including 69 compounds, were tentatively identified in FS products, and high concentrations of neutral PFAS were found in polymer-based products, indicating potential environmental risk. In addition, we applied a simplified data mining process to capture 36 PFAS from the impacted water, and the relationship among FS, AFFF concentrates and impacted water was explored. This study parsed the PFAS characteristics in AFFF-related industrial products and impacted water in China, which is instrumental for managing and controlling prioritized PFAS in this field.

Thermal stability of foams stabilized by fluorocarbon and hydrocarbon surfactants in presence of nanoparticles with different specific surface areas

Mixed dispersions of SiO2 nanoparticles (NPs) with different specific surface areas (SSAs), nonionic surfactants (APG0810) and fluorocarbon surfactants (FS-50) in water were prepared. The molecular interactions in the APG0810/FS-50/NPs dispersions are characterized. Foam volume decay, foam drainage and coarsening under heat are investigated systematically. Results show that the molecular interactions result in the reduction of surface activity and the increase in viscosity and conductivity with increasing in SSAs. The addition of NPs can effectively inhibit foam decay, foam drainage and coarsening under heat, and enhance the corresponding foam thermal stability of the APG0810/FS-50 solutions. The optimal SSA for NPs enhancing foam thermal stability is 300 m2/g. The results can promote the application of NPs in the development of environmentally friendly firefighting foams.

A stabilized foam formulation using FTP‐SDS surfactants for wettability alteration and flow diversion in carbonate fractured oil reservoirs

AbstractFoam injection contributes to improved oil recovery through flow diversion, reduction of interfacial tension (IFT), and wettability alteration of the rock while its stability is an issue. In this article, nitrogen‐foam was optimally formulated using fluorocarbon tubiguard protect (FTP) surfactant stabilized with sodium dodecyl sulfate (SDS) co‐surfactant that was later experimentally considered for oil recovery in a fractured carbonate rock taken from an oil field in the Middle East. The results showed that the 5:1 volume ratio of fluorocarbon surfactant and SDS (FS51) generates a stable foaming agent with ability of changing the wettability of the carbonate rock surfaces to an intermediate gas‐wet state. A series of core‐flood experiments at HPHT conditions were also carried out and designed to properly represent matrix‐fracture media using both a horizontally and vertically oriented setup. The oil saturated cores were flooded with nitrogen gas first followed by foam injection. It was concluded that foam can divert the gas to flow from fractures to the matrix blocks and result in a significant oil recovery. The contact angle tests that performed after core‐flood experiments revealed the wettability changes of fracture surfaces from an oil‐wet to a gas‐wet state. This allows gas to be imbibed into the matrix blocks by capillary force and results in enhancement of ultimate oil recovery. This study revealed that trapped oil in matrixes blocks that had not been drained during the gas injection process could be produced by designing a stable foam that sustainably diverts injected fluid from fractures to matrix zone.