Ethylene Oxide Groups Research Articles

Polyisatin derived ion-solvating blend membranes for alkaline water electrolysis

It is a great challenge to develop membranes based on polyaromatic backbone chemistries that combine high alkaline resistance with high ionic conductivity and low gas crossover for alkaline water electrolysis. Hence, a new alkaline stable aromatic monomer containing side ion-solvating poly(ethylene oxide) (PEO) groups was synthesized and polymerized with isatin and biphenyl via super acid catalyzed hydroxyalkylation to yield ion-solvating copolymers. The prepared aryl-ether free backbone aromatic copolymers (P(IB-PEO)-y) have excellent film-forming properties, high thermal stability, but moderate KOH electrolyte uptake and relatively low conductivity. Therefore, to further enhance the electrolyte uptake and ionic conductivity, P(IB-PEO)-20 copolymers were blended with polybenzimidazole in ratios 80/20, 70/30, 60/40 and 50/50. The prepared blend membranes exhibit high electrolyte uptakes (up to 97 wt%) while the highest ionic conductivity of 110 mS cm−1 at 80 °C was observed for PBI80/P(IB-PEO) blend. The KOH doped PBI70/P(IB-PEO) membrane shows a tensile strength of 20 MPa and a significant increase in Young's modulus (131%) compared to that of PBI80/P(IB-PEO). The alkaline stability test demonstrated that PBI80/P(IB-PEO) membrane exhibits a substantially higher Young's modulus (144% increase) than non-aged analogue, after 1 month in 20 wt% KOH solution at 80 °C. Further, PBI80/P(IB-PEO) and PBI70/P(IB-PEO) membranes retained 96–98% of their original conductivity after aging, indicating their excellent alkaline resistance. Selected membranes were tested in a single cell electrolyzer to probe feasibility and crossover behaviour.

The use of ethoxylated surfactants in flotation concentration of potash ores

This paper studies the use of ethoxylated surfactants (alkylphenols and alkylamines) as flotation collectors for water-insoluble silicatecarbonate impurities contained in potash ores, which form fine slime particles during ore grinding. The highest collector efficiency in flotation desliming of potash ores is achieved with 35 to 45 hydroxyethyl groups in the hydrocarbon radical of the collector. The paper studies the performance of cardanol polyethylene glycol ether, regarded as an alternative slime collector to oxyethylated alkylphenols and alkylamines (currently used at potash flotation plants). It has been shown that in the case of slime flotation in saturated solutions of potassium and sodium chlorides, both when using oxyethylated alkylamines and alkylphenols, as well as alkylcardanol, the best desliming performance is achieved when the hydrocarbon radical of the collector contains 40 ethylene oxide groups. Oxyethylated cardanol is a 100 % undissolved substance, non-flammable and highly soluble in water, with the melting point at around 45 °C. Studies using standard test objects of phyto- and zooplankton have established that the KE-40 flotation agent is not hazardous to the environment. This paper provides industrial use results for this new slime collector obtained in flotation concentration of sylvinite ores of the Verkhnekamskoe deposit. KE-40 enables efficient and selective flotation desliming of potash ores with different contents of water-insoluble silicate-carbonate and anhydrite impurities. It has been adopted for industrial use as an alternative slime collector by Uralkali PJSC.

A methodology for measuring the characteristic curvature of technical-grade ethoxylated nonionic surfactants: the effects of concentration and dilution

Abstract Characterization of the behaviour of commercially available non-ionic surfactants has received considerable attention due to their efficacy in a variety of applications. The main challenge in the application of these types of surfactants is that the hydrophilicity of the surfactant varies with concentration and dilution due to the polydispersity of the ethylene oxide groups. The hydrophilicity of a surfactant can be quantified by the characteristic curvature (Cc) parameter of the hydrophilic–lipophilic difference (HLD) framework. In this work, a model based on natural logarithmic regression was developed to calculate the Cc value of commercial surfactants as a function of surfactant concentration by a fast and simple phase scan. The slope of the Cc curve and the measured Cc at a reference concentration were used to develop the model. The Cc values determined with the model agreed with the measured values from the phase scans. Furthermore, the linear mixing rule proved to be reliable for mixtures of polydisperse ethoxylated surfactants. Finally, the impact of the water-to-oil ratio on the Cc was evaluated and the implications were discussed.

Synthesis and properties of sodium isotridecyl polyoxyethylene ether sulfate with different ethylene oxide addition numbers

Sodium isotridecyl polyoxyethylene ether sulfate (iC13EOnS, n = 5, 7, and 9) with different ethylene oxide (EO) numbers were synthesized by SO3 membrane sulfation process for the first time. The effects of EO number on the equilibrium surface tension, dynamic surface tension, contact angle, and alkali/salt resistance of iC13EOnS were investigated. With the increase of EO consumption, γ cmc increased, but the adsorption efficiency (pC20 ) of surfactant increased. The increase of EO number significantly improved the alkali resistance and salt resistance of iC13EOnS. Additionally, the influence of different electrolytes and their concentrations on the IFT between iCl3EOnS solution and n-decane was also studied. At the same salt concentration, iC13EOnS with shorter EO chains exhibited lower interfacial tension. These results show that the performance of the product can be adjusted by changing the number of EO groups. The study on the relationship between EO number and the performance of iC13EOnS in this article will help to improve the application efficiency of this surfactant.

Robust compound elastomers of integrated polymer cathode and electrolyte for high-performance all-solid-state lithium battery

A novel type of all-solid-state lithium-organic batteries based on redox active multicomponent polyethers comprising stable nitroxide radicals, ethylene oxide groups and cross-linkable moieties has been demonstrated. The radical copolymer with a low glass transition temperature exhibits enhanced mixed conductivities of electron and ion. Furthermore, the in-situ cross-linking of the radical copolymer cathode and a comb-branched polyether electrolyte results in a flexible yet strong compound elastomer, which demonstrates a low interfacial resistance and fast ion transport. The fabricated lithium cell shows a high cycling stability with a low polarization and durable rate capability at room temperature, benefiting from the fast redox reactions in the organic cathode and the integrated structure. This work is expected to advance the development of flexible solid batteries with high electrochemical performance.

Synthesis of the Hierarchical TS-1 Using TritonX Homologues for Hydroxylation of Benzene

The hydrothermal approach was used to effectively synthesis hierarchical TS-1 utilizing the green and inexpensive surfactant TritonX homologues with varying amounts of ethylene oxide groups. The textural property of obtained materials can be modulated by varying the number of ethylene oxide groups of the TritonX homologues. The mesoporous size of hierarchical TS-1 depends on the micelles size of TritonX homologues. The synthesized samples have significant intracrystalline mesopores with a pore size range of 3.5–4.5 nm. The impact of various ethylene oxide group counts of TritonX homologous on the structure, texture properties, and titanium species was investigated using a variety of characterization methods. The hydroxylation of benzene with the H2O2 as oxidizer was used to investigate the catalytic properties of hierarchical TS-1. The catalytic properties and stability of the resulting materials were noticeably improved in the hydroxylation of benzene in comparison with the traditional TS-1.

The mechanism for lowering interfacial tension by extended surfactant containing ethylene oxide and propylene oxide groups

In this work, the interfacial tensions (IFTs) of a series of alkyl ether carboxylates containing different ethylene oxide (EO) and propylene oxide (PO) groups (C12PO15EO5C, C12PO15EO10C and C12PO15EO15C) against n-alkanes were investigated. Based on the experimental and theoretic results, we find that for adsorbed extended surfactant molecules with both PO and EO groups, the PO group stretches towards the oil phase in a helical winding manner, which improves the size of hydrophobic part and decreases IFT. On the other hand, the whole EO group arranges in an “L” pattern with 4 EO flat at the interface and the others stretching into the water. The “dumbbell” type with the large size of the ionic head and PO group at both ends and the linear EO chain in the middle results in the high IFT values. Therefore, a sufficient PO number and few EO number are prerequisites for obtaining ultralow IFT. The addition of NaCl can decrease the size of anionic head and C12PO15EO5C solution can produce ultralow IFT against hydrocarbons at optimized salinity. However, electrolyte shows little effect on the IFTs of extended surfactants with “dumbbell” conformation at the interface because the size of linear EO group plays the crucial role. Our research has important implications for the in-depth understanding of extended surfactants and their application in high-salt reservoirs.

Self-assembly in escin-nonionic surfactant mixtures: From micelles to vesicles

Hypothesis: Saponins are a class of plant derived surfactants which are widely used in food related foams and emulsions, aerated drinks, and in pharmaceuticals and cosmetics. As a potential biosourced and renewable ingredient in a wider range of surfactant based formulations their potential is intimately associated with their mixing with synthetic surfactants. As such the nature of the mixed saponin-surfactant self-assembly is an important characteristic to investigate and understand. The unconventional structure of the saponins compared to the conventional synthetic surfactants poses some interesting constraints on the structures of the mixed aggregates.Experiments: Small angle neutron scattering, SANS, is used to investigate the structure of the saponin, escin, mixed with a range of nonionic surfactants with different ethylene oxide groups, from triethylene glycol monododecyl ether, C12E3, to dodecaethylene glycol monododecyl ether, C12E12.Findings: The scattering data reveal a complex evolution in the solution self-assembled structure with varying escin / nonionic composition and ethylene oxide chain length. The rich structural development comprises of the evolution from the elongated micelle structure of escin to the micelle structure of the nonionic surfactant. At the intermediate solution compositions the structure is predominantly planar, comprising mostly of planar / micellar mixed phases. The nature of the planar structures depend upon the ethylene oxide chain length and the solution composition, and include lamellar, bilamellar vesicle, multilamellar vesicle, and nanovesicle structures, in common with what is observed in other surfactant mixtures.

Physico-chemical characterization of bovine serum albumin-cationic gemini surfactant interaction

Being perspective candidates for bioapplications, gemini surfactant – protein interaction research is continuing extensively. In the work described herein, we have, therefore, investigated the binding of a recently synthesized biodegradable cationic diester-functionalized C14-E2O2-C14 gemini surfactant with ethylene oxide group in the spacer with the transport protein bovine serum albumin (BSA). The system properties were determined through a combination of surface tension measurements, multispectroscopic and computational analyses. The surface and interfacial properties of the concerned gemini got perturbed on interaction with BSA. The reduction in BSA fluorescence intensity was accredited to fluorescence quenching by the surfactant and relevant parameters (KSV and Kb; 14.70, 10.63, 7.27 × 104 M−1 and 25.63, 14.28, 7.20 × 104 M−1) have been computed at three different temperatures (288, 298 and 308 K), which demonstrated that C14-E2O2-C14 binds strongly with BSA protein through static quenching (UV–vis absorption analysis results were the same) with the binding stoichiometry 1:1. The obtained negative values of thermodynamic parameters (ΔGb0,ΔHb0 and ΔSb0) specified spontaneous process where hydrogen bonding and van der Waals forces are the major forces in the interaction mechanism. The effect of β-cyclodextrin (β-CD) has also been explored on the interaction and the values of KSV and Kb have been evaluated. Moreover, some other spectral results (CD, 3-D, synchronous, RRS, pyrene, FT-IR) confirmed that the interaction of the surfactant with BSA persuaded alterations in conformation of BSA. The molecular docking results as well as site probe measurements corroborated the ligand binding sites and interaction of the gemini surfactant with amino acid residues. The binding analysis of C14-E2O2-C14 gemini surfactant-BSA interaction is potentially valuable for elucidating chemico-biological interaction that can be used in the pharmaceuticals, biochemistry and pharmacology arenas.

Molecular insights into the effect of anionic-nonionic and cationic surfactant mixtures on interfacial properties of oil-water interface

The influence of surfactants is of great importance to the interfacial properties, which is related by the characteristics of molecular arrays at the interface of multicomponent and multiphase systems. Comparing with single type of surfactant, the mixtures of surfactants usually provide superior performances in improving interfacial properties of the oil-water interface in the application of enhanced oil recovery. In this study, molecular dynamics simulations were employed to explore the mechanisms and interfacial behaviors at the microscopic level of pure and binary mixture of anionic-nonionic surfactant alcohol ether sulfates (AES) and cationic surfactant dodecyltrimethylammonium chloride (DTAC) at oil-water interface. The results show that the sulfate groups of AES molecules could attract DTAC molecules in the mixed surfactants, thereby reducing the repulsion between the molecules. DTAC molecules present excellent molecular interfacial behaviors, which could improve the arrangement of AES molecules through the interactions between head groups. In addition, it is found that the number of ethylene oxide (EO) group of AES molecules has a great influence on the behaviors of interface. An increase of EO group number could cause AES molecules to exhibit varying degrees of bending. By controlling the proper number of EO group, the aggregation of surfactants could be avoided and satisfactory interfacial properties will be achieved. Moreover, it is observed that the positive charge of DTAC molecule shows a strong repulsion to salt ions, for example Ca2+ ions, thus enhancing the overall salt resistance of mixed surfactants. The molecular-level insights gained in this work could provide useful guidance for designing the surfactant formulations for tertiary/enhanced oil recovery in low-permeability unconventional reservoirs.

Synergism and foam stability in a binary mixture of tea saponin derived from Camellia oleifera Abel and Sodium Lauryl Ether Sulfate

Sodium Lauryl Ether Sulfate, AES, is an anionic surfactant containing ethylene oxide groups, which is widely used in various cosmetic. In this work we investigate the synergism and foam stability in a binary mixture of tea saponin (TS) and AES to promote the development of new formulations and reduce the use of synthetic surfactants in commercial products. The effect of TS addition on interfacial behavior was investigated by interfacial tension (γ) and foam properties, and the interfacial activity was analyzed on different fluid/fluid interfaces at different environments. The results showed that the mixtures of TS with AES displayed synergism in critical micelle concentration (cmc), such as the interaction parameter and thermodynamic parameter. Low concentration of TS addition not only caused the decrease of γcmc, but also improved the stability of the foam. The stability of foams has been interpreted on the basis of bubble distribution size and contact angle. Further study revealed that the interfacial activity of the AES/TS mixture was stable at high temperatures, in the presence of mono (Na+) and divalent (Ca2+ and Mg2+) counterions, and at a pH of 3–11.

Nanoassemblies formed from amphiphilic pillar[5]arene–rod–coil macromolecules in water for the detection of aliphatic diamines

An amphiphilic pillar[5]arene–rod–coil macromolecule (H1) composed of pillar[5]arene, biphenyl, and oligo(ethylene oxide) groups, was synthesized, and its applicability as a soft material for detecting aliphatic diamines was verified. Amphiphile H1 self-assembled into unique nanorings and shows an obvious lower critical solution temperature effect in aqueous solution. Interestingly, nanoaggregates of H1 exhibit certain aggregate-induced emission properties owing to the presence of ten electron-rich biphenyl units on the upper and lower sides of the pillar[5]arene block. In addition, various nanoassemblies were precisely constructed from H1, through the addition of small molecules with electron-acceptor units. This implies that charge-transfer interactions and hydrophilic/hydrophobic effects cooperatively influence the morphology of H1 to form diverse nanoassemblies in water. Moreover, macromolecule H1 with the pillar[5]arene block has a good ability to form host–guest complexes with aliphatic diamines in water, with high selectivity; this significantly affects the process of supramolecular nanoassembly.

Structural Characterization of Nonionic Surfactant Micelles with CO2/Ethylene Oxide Head Groups and Their Temperature Dependence.

Using CO2 as a resource in the production of materials is a viable alternative to conventional, petroleum-based raw materials and therefore offers great potential for more sustainable chemistry. This study presents a detailed structural characterization of aggregates of nonionic dodecyl surfactants with different amounts of CO2 substituting ethylene oxide (EO) in the head group. The micellar structure was characterized as a function of concentration and temperature by dynamic and static light scattering and, in further detail, by small-angle neutron scattering (SANS). The influence of the CO2 unit in the hydrophilic EO group is systematically compared to the incorporation of propylene oxide (PO) and propiolactone (PL). The surfactants with carbonate groups in their head groups form ellipsoidal micelles in an aqueous solution similar to conventional nonionic surfactants, becoming bigger with increasing CO2 content. In contrast, the incorporation of PO units hardly alters the behavior, while the incorporation of a PL unit has an effect comparable to the CO2 unit. The analysis of the SANS data shows decreasing hydration with increasing CO2 and PL content. By increasing the temperature, a typical sphere-rod transition is observed, where CO2 surfactants show a much higher elongation with increasing temperature, which is correlated with the reduced cloud point and a lower extent of head group hydration. Our findings demonstrate that CO2-containing surface-active compounds are an interesting, potentially "greener" alternative to conventional nonionic surfactants.

A systematic research on spontaneous imbibition of surfactant solutions for low permeability sandstone reservoirs

Surfactants, which possess ability to alter rock surface wettability and reduce interfacial tension (IFT), are effective additives for imbibition enhanced oil recovery (IEOR) in low sandstone permeability reservoirs. However, the imbibition efficiencies vary from different surfactants, and some surfactants even have a negative effect on IEOR. Thus, it is necessary to research optimum surfactants suitable for IEOR. Considering that the surfactant properties are closely related to its molecular structure, this study systematically investigated the static imbibition efficiencies of different surfactants based on molecular structures, which contain different surfactant types, ionic head groups, hydrophilicity, and carbon chain lengths. In addition, the imbibition performance of surfactant solutions with different IFTs were also researched. The imbibition tests were conducted with Amott cells at 80 °C, using Changqing low permeability outcrop sandstones. Subsequently, IFT tests, viscosity measurements, contact angle (CA) measurements, and zeta potential tests were conducted to explore the IEOR mechanisms of different surfactant solutions. The experimental results showed that the IEOR potential of different types of surfactants was: anionic > nonionic > brine > amphoteric > cationic. Sulfate anionic surfactants showed better ability of wettability alteration than sulfonate surfactants, and achieved the most imbibition efficiency. Increasing the hydrophilicity of surfactants by introducing the ethylene oxide (EO) groups to the surfactant structures was effective in enhancing wettability alteration ability of surfactants and improving imbibition recovery. Surfactants with longer carbon chain (C16 surfactants) enhanced more imbibition recovery than short carbon chain surfactants (C12 surfactants), which was mainly depending on better IFT reduction ability of C16 surfactants than C12 surfactants. Appropriate IFT reduction, such as 10−1 mN/m levels, which reduced the adhesion work, enhanced the gravity dominated imbibition and avoided too much capillary pressure reduction, was the most desirable for IEOR. Too low IFTs, such as less than 10−2 mN/m, were not suitable for IEOR, because the capillary pressure reduced greatly, resulting in the imbibition process mainly dominated by gravity. This study provides fundamental information about the selection and design of surfactants for IEOR in low sandstone permeability reservoirs.

Solid Polymer Electrolytes with Increased Polymer Polarizability for Solid-State Lithium Batteries

Solid polymer electrolytes (SPE) are light-weight, flexible, and non-flammable, thus providing a promising technical route to practical solid-state lithium batteries. Although a broad variety of molecular structures of the solid polymer matrices are described in the literature, commercially available materials are scarce. The mostly widely studied example of SPE are the poly(ethylene oxide) (PEO)-based electrolytes that contain a small molecule Li-salt (e.g., LiPF6, LiTFSI, etc). However, solid-state batteries made with a PEO-based SPE are only operational above 60 °C, corresponding to the melting of PEO, where their mechanical strength is poor. The room-temperature performance of PEO-SPEs are too low (< 10-5 S/cm) to be practical [1]. Thus, new polymer electrolytes that have high Li+ conductivity and high mechanical strength are needed.The migration of Li+ in PEO-SPE depends on the coordination of Li+ by the ethylene oxide (EO) segment, which normally involves 6-8 EO moieties. The interaction of Li+ with an EO segment is strongly influenced by the polarizability of the EO groups. The relative permittivity (ε) of a single ethylene oxide (CH2CH2O) is only about 13 – 14 [2]. This implies that Li ions experience much weaker interactions with EO groups than other polar molecules, like water (ε = 80) or cyclic carbonates (e.g., ethylene carbonate, ε = 90). Thus, one approach to increase the interaction of Li+ with the polymer chain could be to increase the polarizability of the polymers themselves. Many functional groups are highly polarizable. But only those groups that can be linked to the PEO main chain are worthy of consideration here. An example is vinylene carbonate (VC, ε = 126), which contains double bonds and can be added to the EO chains to form new polymer electrolytes.In order to link VC groups to EO chains, a PEO-like SPE may be formed using in-situ radical polymerization of the EO precursors. Examples of such precursors include poly(ethylene glycol) dimethacrylate, poly(ethylene glycol) diacrylate or their derivatives. Small molecule Li-salts may be incorporated in the precursor solution. The polymerization can be initiated by UV light irradiation or by thermal heating, depending on the type of radical initiator. In this method, the intimate interactions between Li-ions and EO groups are ensured and the crystallization of the EO segments is largely prevented.In this work, we combine these approaches to form a new solid polymer electrolyte that has good conductivity and high mechanical strength. The membrane is formed in-situ using UV irradiation of a blend of precursors and salts and chain additive functional molecules. This resulting SPE has high conductivity (0.3 mS/cm at room temperature and 1.1 mS/cm at 70 °C), a wide electrochemical stability window up to 4.8 V (vs. Li+/Li) and is thermally stable to ~200 °C, while resisting penetration of Li metal dendrites. The application of the polymer electrolyte in a SiO composite electrode is also demonstrated to achieve high capacity.

Synthesis, Characterization, and CO2/N2 Separation Performance of POEM-g-PAcAm Comb Copolymer Membranes.

Alcohol-soluble comb copolymers were synthesized from rubbery poly(oxyethylene methacrylate) (POEM) and glassy polyacrylamide (PAcAm) via economical and facile free-radical polymerization. The synthesis of comb copolymers was confirmed by Fourier-transform infrared and proton nuclear magnetic resonance spectroscopic studies. The bicontinuous microphase-separated morphology and amorphous structure of comb copolymers were confirmed by wide-angle X-ray scattering, differential scanning calorimetry, and transmission electron microscopy. With increasing POEM content in the comb copolymer, both CO2 permeability and CO2/N2 selectivity gradually increased. A mechanically strong free-standing membrane was obtained at a POEM:PAcAm ratio of 70:30 wt%, in which the CO2 permeability and CO2/N2 selectivity reached 261.7 Barrer (1 Barrer = 10−10 cm3 (STP) cm cm−2 s−1 cmHg−1) and 44, respectively. These values are greater than those of commercially available Pebax and among the highest separation performances reported previously for alcohol-soluble, all-polymeric membranes without porous additives. The high performances were attributed to an effective CO2-philic pathway for the ethylene oxide group in the rubbery POEM segments and prevention of the N2 permeability by glassy PAcAm chains.

Structure and dynamics of an aqueous solution containing poly-(acrylic acid) and non-ionic surfactant octaethylene glycol n-decyl ether (C10E8) aggregates and their complexes investigated by molecular dynamics simulations.

A detailed molecular dynamics simulation study of the self-assembly, intermolecular structure and thermodynamic behavior of an aqueous solution of non-ionic surfactant octa ethylene glycol n-decyl ether (C10E8) in the presence of a non-ionic polar polymer poly(acrylic acid) PAA is presented. The aggregation number Nagg and concentration of surfactant Cs in the simulation systems were varied in the range 0.01-0.32 M and 5 < Nagg < 101 (dilute to concentrated) with a dilute polymer concentration (Cp = 0.01 M). Lamellar aggregates of non-ionic surfactant in bulk aqueous solution are shown by molecular level computations for the first time. Spherical micellar aggregates and lamellar aggregates are formed at low and high Nagg, respectively. The transition from the spherical micelle phase to the lamellar phase in a binary solution is captured for the first time. A conformational transition from coiled to extended PAA chains adsorbed on the surfactant aggregate occurs at a particular value of Nagg, commensurate with the transition from spherical micelle aggregates to anisotropic lamellar aggregates. Formation of the surfactant aggregate in binary and ternary solutions and the polymer-surfactant complex in a ternary solution is enthalpically favored. Adsorption of PAA on the surfactant aggregate surface is driven by hydrogen bonds (HBs) between carboxylic acid groups of PAA and ethylene oxide groups of C10E8. A significant number of HBs occur between polar oxygens of C10E8 and hydroxyl oxygens of PAA. The results are in agreement with the limited available experimental data on this system.

Pickering emulsions stabilized by thermoresponsive oligo(ethylene glycol)-based microgels: Effect of temperature-sensitivity on emulsion stability

HypothesisThe stability of emulsions stabilized by soft and responsive microgels and their macroscopic properties are governed by the microstructure of microgels, in particular their deformability. However, little is known about the role of the microgel chemistry, though it is expected that polymeric backbone with an amphiphilic structure is a requirement for their adsorption at the oil-water interface. ExperimentsA series of biocompatible, thermoresponsive and amphiphilic poly(oligoethylene glycol)methacrylate (pOEMA) microgels is synthesized, with varying hydrophobic-hydrophilic balance, or equivalent varying volume phase transition temperature (VPTT). Their behavior in the bulk phase and at solid interfaces is compared to their behavior at liquid interfaces, studied on flat and model interfaces by the pendant drop method, and on drops, in microgel-stabilized emulsions. FindingsControlling the composition of microgels by simply changing the number of ethylene oxide groups in the hydrophilic side chain allows a precise tuning of their VPTT in the range of 20–60 °C. Simultaneously, the swelling ratio and the deformability of the microgels increase by increasing the hydrophilicity, as a result of the polymerization process. Regardless of their hydrophilicity, all the swollen pOEMA microgels adsorb at the liquid interface and stabilize emulsions, whose flocculation state and mechanical stability depends on the microgel deformability. Unexpectedly, most emulsions remain stable upon heating above the VPTT of the microgels. Such feature highlights their extreme robustness, whose origin is discussed. This study opens new opportunities for the use of biocompatible Pickering emulsifiers.

Effect of Ethylene Oxide Group in the Anionic–Nonionic Mixed Surfactant System on Microemulsion Phase Behavior

AbstractThe phase behavior of microemulsions stabilized by a binary anionic–nonionic surfactant mixture of sodium dihexyl sulfosuccinate (SDHS) and C12‐14 alcohol ethoxylate (C12 − 14Ej) that contains an ethylene oxide (Ej) group number, j, of either 1, 5, or 9 was investigated for oil remediation. The oil–water interfacial tension (IFT) and optimal salinity of the microemulsion systems with different equivalent alkane carbon numbers (EACN) were examined. The anionic–nonionic surfactant ratio was found to play a pivotal role in the phase transition, IFT, and optimal salinity. The minimum IFT of mixed SDHS − C12 − 14Ej systems were about three times lower than those of neat SDHS systems. A hydrophilic–lipophilic deviation (HLD) empirical model for the mixed anionic–nonionic surfactant system with the characteristic parameter was proposed, as represented in the excess free energy term . The results suggested that the mixed system of SDHS − C12 − 14E1 was more lipophilic, while SDHS − C12 − 14E9 was more hydrophilic than the ideal mixture (no excess free energy during the microemulsion formation), and the SDHS − C12 − 14E5 system was close to the ideal mixture. The findings from this work provide an understanding of how to formulate mixed anionic–nonionic microemulsion systems using the HLD model for oils that possess a wide range of EACN.

The effect of ethylene oxide groups in dodecylamine polyoxyethylene ether on rtutile flotation

The effect of ethylene oxide groups in dodecylamine polyoxyethylene ether on rtutile flotation