Hydrophobic Chain Length Research Articles

Hydrophobically Associating Polyacrylamide “Water-in-Water” Emulsion Prepared by Aqueous Dispersion Polymerization: Synthesis, Characterization and Rheological Behavior

The hydrophobically associating polyacrylamide (HAPAM) is an important kind of water-soluble polymer, which is widely used as a rheology modifier in many fields. However, HAPAM products prepared in a traditional method show disadvantages including poor water solubility and the need for hydrocarbon solvents and appropriate surfactants, which lead to environmental pollution and increased costs. To solve these problems, we reported a novel kind of HAPAM "water-in-water" (w/w) emulsion and its solution properties. In this work, a series of cationic hydrophobic monomers with different alkyl chain lengths were synthesized and characterized. Then, HAPAM w/w emulsions were prepared by the aqueous dispersion polymerization of acrylamide, 2-methylacryloylxyethyl trimethyl ammonium chloride and a hydrophobic monomer. All these emulsions can be stored more than 6 months, showing excellent stability. An optical microscopy observation showed that the particle morphology and the particle size of the HAPAM emulsion were more regular and bigger than the emulsion without the hydrophobic monomer. The solubility tests showed that such HAPAM w/w emulsions have excellent solubility, which took no more than 180 s to dilute and achieve a homogeneous and clear solution. The rheology measurements showed that the HAPAM association increases with a hydrophobe concentration or the length of hydrophobic alkyl chains, resulting in better shear and temperature resistances. The total reduced viscosity was 124.42 mPa·s for cw101, 69.81 mPa·s for cw6-1, 55.38 mPa·s for cw8-0.25, 48.95 mPa·s for cw12-0.25 and 28 mPa·s for cw16-0.25 when the temperature increased from 30 °C to 90 °C. The cw8-2.0 that contains a 2 mol% hydrophobe monomer has the lowest value at 19.12 mPa·s due to the best association. Based on the excellent stability, solubility and rheological properties, we believe that these HAPAM w/w emulsions could find widespread applications.

Simultaneous enhancement of critical heat flux and heat transfer coefficient via in-situ deposition of ionic liquids during pool boiling

Two-phase heat transfer processes such as boiling are required to address waste heat management challenges. Among the various regimes, the nucleate boiling regime, which relies on the ebullition cycle to dissipate large amounts of heat within narrow temperature budgets is desired in such applications. However, an insulating vapor blankets the heater at higher heat fluxes to interrupt this high heat transfer coefficient (HTC) regime. This limiting heat flux beyond which a thermal runaway occurs in boiling systems is known as the critical heat flux (CHF). Accordingly, easy-to-implement and reliable strategies for simultaneous enhancement in HTC and CHF are desired. Typical surface modification/coating strategies used in this regard are often expensive and suffer from the issues of delamination and fouling. Here we utilize aqueous solutions of imidazolium ionic liquids (ImILs) to propose a facile, scalable, and robust strategy to address these issues. We show that the in-situ deposition of short-chain ImILs such as [C2mim][Cl] enhances heater surface wettability to remarkably increase the CHF to ≈1600kW/m2, i.e., ≈1.6× increase compared to the baseline case of pure water. We explain the mechanism of this atypical CHF enhancement with molecular additives via thorough surface tension, foamability, surface, and wettability characterization experiments. We next vary the hydrophobic chain length of the ImILs to facilitate a simultaneous enhancement in CHF and HTC. We perform a quantitative comparison with the existing studies in the literature to demonstrate the potential of our approach. Ease of implementation along with the flexibility to favorably manipulate the heater surface and the boiling fluid properties simultaneously by tuning the structure of ImILs are promising for current and future thermal management challenges.

Probing the interactions of dansyl appended sequence-defined oligomers with serum albumins: Effect of functionality, hydrophobicity, and architecture

In this work, a library of functionally and structurally tuneable macromolecules were synthesised and their interaction with serum proteins were studied experimentally and theoretically, with an aim to identify the driving factors that influence protein-drug interaction. The parameters taken for assessment were (a) the number and type of functional groups (dithiocarbamate, ester and amide) present in the backbone and sidechain, (b) different architectures including linear and branched, and (c) hydrophobic/hydrophilic character. Dansyl moiety was attached to make these macromolecules a suitable acceptor for FRET with serum proteins. The binding constant values calculated from the fluorescence titrations indicated that an optimum hydrophobic character, chain length and architecture are essential for a favourable interaction with BSA/HSA. By changing the above mentioned three factors, we were able to achieve a wide range of binding constant values in the range of (2.99–7.91) × 104 M−1 for BSA and (1.64–11.7) × 104 M−1 for HSA. The number of binding sites varied from 1.13 to 1.69 for BSA and 0.89 to 1.35 for HSA. Also, the energy transfer efficiency was calculated and it falls in the range of 63.9–88.7% and 52.0–84.2% respectively for BSA and HSA. The quenching mechanism for serum protein-drug complex was found to involve both static and dynamic quenching. Moreover, this structure–activity relationship was also backed by molecular docking studies.

PANF supported polymeric ionic liquids: Amphiphilic microenvironment for efficient preparation of biodiesel

Efficient and green production is extremely essential to the development of society and environment, and supported polymeric ionic liquids as heterogeneous catalysts are the current research hotspot for chemists. In this study, imidazolium ionic liquids were supported on modified polyacrylonitrile fiber (PANF) by reversible addition fragmentation chain transfer (RAFT) polymerization, and a series of fiber-supported basic catalysts (PANF@VIm-nX) were obtained by ion exchange with different anions. The modified fibers were characterized by FT-IR, XRD, TGA, SEM, 13C CP-MAS NMR and ICP-MS. The results show that the modified fibers are successful and the catalysts have sufficient active sites and mechanical strength to meet the application requirements. Several supported poly(ionic liquid)s catalysts were used to promote the transesterification of methanol and soybean oil to produce biodiesel. The effects ofionicliquidswith different structures on the reaction yield were sufficiently investigated. The anions of ionic liquids and the length of hydrophobic alkyl chains have synergistic effects on the catalytic performance of the catalyst. The fiber catalyst (PANF@VIm-8OMe) with 8 carbon alkyl chains and OMe anion showed the optimal catalytic efficiency. The yield of biodiesel was as high as 95.4 % within 6 h with a catalyst dosage of 4 wt% and a methanol to oil ratio of 30:1 at 60 ℃. In addition, the fiber catalyst had excellent stability and durability, which could be recycled more than 6 times. Finally, the fiber could be twined on the stirring impeller of the reactor, indicating its potential industrial application prospect.

Discerning perturbed assembly of lipids in a model membrane in presence of violacein: Effects of membrane hydrophobicity

For the lack of effective antibiotics towards antibiotic resisting bacteria, it is required to discover new antibiotics and to understand their antimicrobial mechanism. Violacein is a violet pigment found in several gram-negative bacteria possessing antimicrobial properties to gram-positive bacteria. This present article investigates the insertion ability of this molecule into a model membrane composed of zwitterionic phospholipids. Thermodynamic characterization of lipid monolayers in the presence of violacein was carried out using a single lipid layer formed at air-water interface. The molecule inserts into the layer altering the area occupied by each lipid and the in-plane compressibility of the film. This insertion increases with the hydrophobic chain length of the lipid. The perturbed self-assembly of lipids in a bilayer is quantified using a lipid multilayer system applying the X-ray reflectivity technique. The electron density profile from the reflectivity data shows that the molecule inserts into the fluid phase creating a relatively ordered chain conformation. Further, the insertion into the gel phase is observed to increase with the increased thickness of the hydrophobic core of a bilayer.

Feasibility evaluation of novel anionic-nonionic gemini surfactants for surfactant-enhanced aquifer remediation

Surfactant-enhanced aquifer remediation (SEAR) can effectively remove residual dense non-aqueous phase liquids. In this work, a series of environment-friendly anionic-nonionic gemini surfactants, namely, ethylene glycol succinate polyoxyethylene sulfonate (GEOnS-m, n = 3, 5 and 7; m = 10 and 12), were synthesized and evaluated for application in SEAR. The critical micelle concentrations of GEOnS-m were 2.14 × 10−3–1.62 × 10−2 mM, and the molar solubilization ratios of GEOnS-m for tetrachloroethylene were 1.93–3.44, which were 1.5–5 times higher than traditional surfactants. The GEOnS-m solutions remained stable at 5–25 °C, 50 mM salt, and pH = 5.0–9.0. The micelle size decreased as the temperature decreased, which reduced the solubilization capacity (24.9%–37.0%) of the GEOnS-m solutions. Inorganic salts could improve the solubilization capacity of the GEOnS-m solutions by promoting micelle polymerization and increasing the hydrophobic core volume for solubilizing tetrachloroethylene. This work found that 0.80%–4.00% of GEOnS-m adsorbed on the media during simulated column flushing, which was less than the traditional surfactants due to stronger electrostatic repulsion between the micelles and the media. Meanwhile, the solubilization capacity of GEOnS-m was positively correlated with the hydrophobic carbon chain length, while, the adsorption amount in the media and application cost of GEOnS-m were positively correlated with the EO number and negatively correlated with the hydrophobic carbon chain length. Comprehensive evaluation results revealed that GEO3S-12 was preferred for SEAR. This work not only developed suitable surfactants for SEAR but also attempted to further the rational design of surfactants for diverse applications by combining different functional groups into one molecule.

Cationic lipid-conjugated bis-arylidene oxindole derivatives as broad-spectrum breast cancer-selective therapeutics

Breast cancer is a heterogeneous malignancy with wide-ranging variations in therapeutic responses, overall survival etc. Major challenges for available chemotherapeutic agents in achieving clinical success are in maintaining systemic bio-distribution and avoiding non-specific adverse effects. Bis-arylidene oxindoles are estrogen receptor (ER)-selective bioactive molecules with moderate potency. In here, we have designed, synthesized and evaluated a series of twin aliphatic chain cationic lipid-conjugated bis-arylidene oxindole molecules with variations in nature of linker, lengths of carbon spacer and hydrophobic twin chains. We observed that among the various structural analogues, C8 twin-chain containing molecules, PGC8, S2C8 and S3C8 showed effective cancer cell-selective cytotoxicity in different cancer cell lines with an IC50 ranging from 4 to 7 µM. These molecules selectively induced apoptosis, ROS production and cell cycle inhibition at G1/S phase in ER + breast cancer cells but not in non-cancer cells. Additionally, these molecules formed homogenous self-assemblies exhibiting effective hydrodynamic diameter with positive surface charge. The self-assemblies also showed prominent cancer cell-selective uptake and DNA-binding abilities. Hence, we have shown successful incorporation of dexamethasone to the self-assemblies, and its enhanced cytotoxicity even in ER-negative breast cancer cells. All these results indicate that PGC8, S2C8 and S3C8 molecules, albeit their potent and selective ER-positive anti-breast cancer activity, can be repurposed as targeted delivery systems and hold promise as unique, broader spectrum breast cancer cell-selective therapeutic payloads.

Promising potential of bio-sourced amphiphilic xanthan as an emulsifier in O/W dispersions

The emulsification properties of hydrophobically modified xanthan (HMX) obtained through green esterification using alkenyl succinic anhydrides (ASA) as grafting agents were investigated by preparing oil-in-water emulsions without adding any surfactant, in order to better understand the stability phenomenon at the oil-water interface. This study demonstrated that new-brand bio-sourced HMX owns emulsifying potential compared to pristine xanthane, known for its poor interfacial properties as a non-absorbing polymer. A complete approach for studying the stability of the dispersions was carried out at different levels: a) macroscopic level: visual identification of stability, b) microscopic level: coupled optical microscopy and droplet size distribution and c) deep microstructure stability monitoring over time by Static Multiple Light Scattering. First, a series of HMX differing in alkenyl chain length and grafting density added at 0.2% w/w in emulsions were compared. Increased grafting density or hydrophobic chain length provided a highly stable and homogeneous emulsion over 30 days. In the case of less stable emulsions, two solutions are proposed: 1) increasing HMX concentration thus improving emulsifying properties, 2) adding native xanthan as a thickening agent, which slows down the creaming destabilization mechanism. This original article shows that the new-brand bio-sourced amphiphilic xanthan obtained under green modification synthesis behave promising and effective emulsifying capacities to stabilize oil-in-water emulsions, which offers promising potential for industrial applications.

Preparation of zwitterionic ionic surfactants-based sulphonyl for steel protections: Experimental and theoretical insights

Abstract Designating an organic inhibitor with a specific chemical structure that actively participates in steel protection by increasing adsorption on the steel surface. Based on that, we synthesized three zwitterionic surfactants based on azomethine with different hydrophobic chain lengths labeled ZWSO, ZWSD, and ZWSH. The presence of azomethine group, electrons, and heteroatoms in the zwitterionic surfactant’s amphipathic structure helped to improve C-steel protection. Their inhibitory activity toward steel corrosion was investigated utilizing electrochemical impedance spectroscopy (EIS), gravimetrical, and potentiodynamic polarization techniques. Importantly, the surfactant tail influenced corrosion inhibition performance; as surfactant tail length increased, so did inhibition efficiency due to increased adsorption affinity. The inhibition efficiencies of ZWSO, ZWSD, and ZWSH are 87.15, 89.82, and 91.36%, respectively. Tafel data clarified that ZWSO, ZWSD, and ZWSH inhibitors behave as mixed-type inhibitors following the modified Langmuir isotherm. The inhibitors can adsorb physiochemically on the steel surface with ∆G ads ranges from −38.48 to −44.6 kJ mol−1. The SEM confirms that the morphology of C-steel becomes smoother because of inhibitor adsorption. The DFT and MCs output data supported the experimental performance of the tested ZWSO, ZWSD, and ZWSH inhibitors and especially their dependence on surfactant tail length.

Biocompatible cationic polypeptoids with antibacterial selectivity depending on hydrophobic carbon chain length.

The overuse of antibiotics has triggered a new infection crisis and natural antimicrobial peptides (AMPs) have been extensively studied as an alternative to fight microorganisms. Polypeptoids, or polypeptide-biomimetics, offer similar properties to polypeptides and a highly tunable structure that has been synthesized by various methods such as ring opening polymerization (ROP) using N-carboxyanhydride monomers. Simultaneous high antibacterial activity and biocompatibility of a structure by efficient synthesis is desired in the application of those materials. Herein, a series of cationic polypeptoids (PNBs) with variable side chain lengths was obtained by introducing positive charges to the main chain in one step and preserving the backbone structure, namely polypeptoids (PNBM, PNBE, PNBB) with different end groups (methyl (M), ethyl (E), butyl (B)). To address the issue of infection in interventional biomedical implants, we report cost-effective modified polyurethane (PU) films (PU-PNBM, PU-PNBE, PU-PNBB) as physical-biological synergistic antibacterial surfaces that overcome problems such as steric hindrance and the solubility of the materials. Antibacterial selectivity was achieved by regulating the different side chain lengths. When methyl and ethyl were used as hydrophobic side chains, they can only selectively kill Gram-positive Staphylococcus aureus. PNBB, the most hydrophobic and with a butyl side chain can kill both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus and inhibit the growth of bacterial biofilms. Effective in both solution and modified substrate, its biocompatibility is not compromised while the antibacterial properties are substantially improved. Furthermore, PU-PNBB films demonstrated their potential in vivo antimicrobial efficiency in a model of S. aureus infection established on mouse skin. The synthesis route and the surface modification strategies are convenient, providing a solution to the problem of poor biocompatibility in antimicrobial surface applications and a strategy for the use of peptide polymers for targeted therapy after specific infections in the biomedical field.

Host defense peptide-mimicking β-peptide polymer displaying strong antibacterial activity against cariogenic Streptococcus mutans

• A host defense peptide-mimicking β -peptide polymer tbubz-(DM 50 :CH 50 ) 30 shows superior antibacterial efficiency than metronidazole against S. mutans biofilm. • The β -peptide polymer inhibits the formation of S. mutans biofilm. • The β -peptide polymer disperses mature S. mutans biofilm. • The β -peptide polymer exhibits high antibacterial activity and low cell toxicity. Cariogenic Streptococcus mutans ( S. mutans ) is a leading cause of bacterial-induced oral diseases. Current strategies to kill bacteria based on Host defense peptide (HDP) mimicking polymers hold promise to treat oral bacterial infection. Here, we explore the impact of hydrophobic subunit and chain length variation on the antibacterial and antibiofilm activity of β -peptide polymers. The physicochemical and biological properties, such as the toxicity, the antibacterial activity, and the effect on bacterial transcription of β -peptide polymers, were systematically investigated with numerous techniques. The results exhibited that the optimal β -peptide polymer has low toxicity towards human periodontal ligament fibroblasts, and β -peptide polymers (especially P3) have more excellent antibacterial activity against S. mutans than metronidazole. In addition, β -peptide polymers inhibited the reversible and irreversible bacterial adhesion during the formation of biofilms. The polymer can promote biofilm dispersion by decreasing the hydrophobicity of bacterial cells after adhering to cell surfaces. Analysis of the transcriptome for S. mutans treated with β -peptide polymers demonstrated that β -peptide polymers could reduce the cariogenicity of S. mutans by impacting the transcription of the energy and acid metabolism-related genes. β -peptide polymers are promising antimicrobial agents in clinical dentistry due to their high antibacterial efficiency and low toxicity.

Influence of Hydrophobic and Hydrophilic Chain Length of CiEj Surfactants on the Solubilization of Active Pharmaceutical Ingredients.

Up to 90% of all newly developed active pharmaceutical ingredients (APIs) are poorly water soluble, most likely also showing a low oral bioavailability. In order to increase the aqueous solubility of these APIs, surfactants are promising excipients to increase both solubility and consequently bioavailability (e.g., in lipid- and surfactant-based drug delivery systems). In this work, we investigated the influence of hydrophobic and hydrophilic chain lengths of CiEj surfactants (C8E6, C10E6, and C10E8) toward the solubilization of fenofibrate, naproxen, and lidocaine. Furthermore, we investigated the partitioning of these APIs between the surfactant aggregates and the surrounding aqueous bulk phase. For all APIs considered, we determined the locus of API solubilization as well as the individual aggregation numbers (Nagg) of surfactants and API molecules in an API/surfactant aggregate. We further determined the hydrodynamic radius (Rh) of the API/surfactant aggregates in the absence and presence of the APIs. The size of the API/surfactant aggregates (Nagg, Rh) passes through a minimum upon lidocaine solubilization; it gradually increases upon naproxen solubilization and is almost constant upon fenofibrate solubilization. The results give valuable insights into the solubilization mechanisms of APIs in the CiEj surfactant aggregates. Our results reveal that fenofibrate is solely solubilized in the hydrophobic core of the CiEj surfactant aggregates, as only the hydrophobic chain length of the surfactant influences its solubilization. Naproxen is solubilized in the palisade layer of the surfactant aggregates, as both the hydrophobic and hydrophilic chain lengths are decisive for its solubilization. Lidocaine is mainly solubilized in the rather hydrophilic corona region of the surfactant aggregates, as the hydrophilic chain length of the surfactant governs its solubilization. The results further reveal that the hydrophilic/lipophilic balance is not an appropriate measure to estimate the solubilization capacity of surfactant aggregates.

Investigation of an anaesthetic drug (tetracaine hydrochloride) in the presence of ionic fluid and surfactant: Mixed micellization & spectroscopic studies

The effect of ionic liquid and cationic surfactant on the physicochemical characteristic of an anaesthetic drug (tetracaine hydrochloride, TCH) has been studied in the current task. The ionic fluid (1-hexadecyl-3-methyl imidazolium chloride, SAIL) and cationic surfactant (cetylpyridinium chloride, CPC) used in this study are of the same hydrophobic chain length. Tensiometric and absorption spectroscopic methods have been castoff to study the interaction of TCH with SAIL/CPC. The critical micelle concentration (cmc) values of single and mixed amphiphiles were computed by the surface tension method. In addition to cmc, maximum surface excess concentrations (Γmax), minimum surface areas per surfactant molecule (Amin), surface tension at the cmc (γcmc), surface tension reduction efficiency (πcmc), and several thermodynamic parameters of mixed micellization were measured. The calculated average value for the interaction parameter (βRub) suggests TCH show higher synergistic interaction with SAIL compared to CPC. The better attractive interaction (synergism) between SAIL and TCH is also confirmed by UV–visible spectroscopy. The absorption spectra of the drug show increase in the absorption with increasing the concentration of surfactants without any shift confirming the formation of a new complex. The binding constant value is more for the TCH + SAIL mixture.

Antifouling graphene oxide membranes for oil-water separation via hydrophobic chain engineering

Engineering surface chemistry to precisely control interfacial interactions is crucial for fabricating superior antifouling coatings and separation membranes. Here, we present a hydrophobic chain engineering strategy to regulate membrane surface at a molecular scale. Hydrophilic phytic acid and hydrophobic perfluorocarboxylic acids are sequentially assembled on a graphene oxide membrane to form an amphiphilic surface. The surface energy is reduced by the introduction of the perfluoroalkyl chains while the surface hydration can be tuned by changing the hydrophobic chain length, thus synergistically optimizing both fouling-resistance and fouling-release properties. It is found that the surface hydration capacity changes nonlinearly as the perfluoroalkyl chain length increases from C4 to C10, reaching the highest at C6 as a result of the more uniform water orientation as demonstrated by molecular dynamics simulations. The as-prepared membrane exhibits superior antifouling efficacy (flux decline ratio <10%, flux recovery ratio ~100%) even at high permeance (~620 L m−2 h−1 bar−1) for oil-water separation.

Effect of Ionic and Non-Ionic Surfactants on the Pasting Characteristics and Digestive Properties of Regular and Frozen Starch for Oral Delivery.

Starch is an ideal wall material for controlled release in oral delivery systems due to its non-allergic properties, availability, and cheap price. However, because of its poor mechanical behavior and high water permeability, it is necessary to modify the amphiphilic nature of starch. Surfactants are essential components to emulsify the lyophobic food ingredients. However, the interaction of starch with emulsifiers and how they affect the pasting behavior and digestion of starch are not well understood. In this paper, surfactants, such as non-ionic Tween (TW) and ionic sodium fatty acid (NaFA), with varying hydrophobic carbon chain lengths, were selected as model amphiphiles to investigate the structural, pasting, rheological properties and in vitro digestibility of regular and frozen starch samples. The results showed that, in most cases, the addition of TW reduced the viscosity of starch. However, saturated medium-chain NaFA increased the starch viscosity and rheological modulus greatly. Both surfactants inhibited starch digestion. This paper presents a comparative investigation on the effect of ionic and non-ionic surfactant on the structure and properties of corn starch, and therefore the information is useful for structural-based formulation with starch for developing colloidal delivery systems. It is also helpful for developing functional food with controllable digestion properties.

Effects of Fatty Alcohols with Different Chain Lengths on the Performance of Low pH Biomass-Based Foams for Radioactive Decontamination.

Compared with polymers and nanoparticles, fatty alcohols can not only increase the stability of foam, but also maintain better foamability at pH < 2, which is beneficial to reduce waste liquid and increase decontamination efficiency for radioactive surface pollution. However, different fatty alcohols have different hydrophobic chain lengths. The effects of fatty alcohols with different chain lengths on the performance of decontamination foam were studied at pH < 2, to assist in the selection of suitable fatty alcohols as foam stabilizers. Combined with betaine surfactant and phytic acid, biomass-based foams were synthesized using fatty alcohols with different chain lengths. When the hydrophobic tail groups of the fatty alcohol and the surfactant were the same, the foam showed the best performance, including the lowest surface tension, the highest liquid film strength, the greatest sag-resistance and the best stability. However, when the hydrophobic tail groups were different, the space between adjacent surface active molecules was increased by thermal motion of the excess terminal tail segments (a tail-wagging effect), and the adsorption density reduced on the gas-liquid interface, leading to increased surface tension and decreased liquid film strength, sag-resistance and stability. The use of decontamination foam stabilized by fatty alcohols with the same hydrophobic group as the surfactant was found to increase the decontamination rate of radioactive uranium pollution from 64 to over 90% on a vertical surface.

Synthesis of tetramethylpiperidine 1-oxyl-based functional ionic liquids (FTILs), volumetric properties and thermodynamics of the activation for viscous flow of (FTILs + water) binary systems

The application of tetramethylpiperidine 1‑oxyl (TEMPO)-based ionic liquids is a newly emerging area in the fields of the extraction natural compounds. Herein, TEMPO-based functional ionic liquids (FTILs) [CnTr][TEMPO-OSO3] (n = 2, 4, 6, 8, 10, 12, 14, 16) were synthesized and characterized by FT-IR, 1H NMR, 13C NMR and high-resolution mass spectrometry. The volumetric properties and thermodynamics of the activation for viscous flow of (FTILs + water) binary systems were measured. Under the experimental conditions, with the increase of hydrophobic side chain length, the interaction between FTILs and solvent decreases and the interaction between FTILs ions and FTILs ions increases. The FTILs are water-structure-making solutes. The activation process of the solutes for viscous flow of the binary systems is an isocoulomb reaction. A semi-empirical method is an effective method to predict the viscosity of the binary systems within a certain concentration range (m < 0.9 mol·kg−1).

Effect of linking groups and hydrophobic groups on properties of sulfate Gemini surfactants

From the perspective of molecular design, a series of sulfate Gemini surfactants with different hydrophobic chains and linking groups were synthesized by etherification, ring opening and sulfation. The structures of the products were characterized by IR and 1H NMR. The synthesized sulfate Gemini surfactants had good heat resistance, especially the surfactants with rigid linking groups, measured by thermogravimetric analysis. The synthetic surfactants had low Krafft points, wherein the Krafft points of the surfactants with a carbon chain of 12 were <0 °C. With increasing hydrophobic carbon chain length or decreasing methylene number of linker, their CMC and γcmc first decreased and then increased. The γcmc of surfactants with rigid linking groups were higher and their CMCs were lower. It is analyzed by the calculated surface activity parameters (pC20, Γmax, Amin) that with increasing hydrophobic chain length, the surface activity of synthetic surfactants increased first and then decreased, and the surfactant with hydrophobic carbon chain C14 had the best surface activity. The influences of the length of the linking group and the hydrophobic group on the emulsifying capacity, wetting property, calcium soap dispersion and foam property of the surfactants were also analyzed. It was an attempt to explore and design excellent Gemini surfactants.

Synthesis and properties of sodium fatty acyl lactylates

Sodium fatty acyl lactylates (Cn lactylates), which are a class of biomass-based surfactants, were synthesized from fatty acids and lactic acid via a two-step reaction. The equilibrium surface tensions, dynamic surface tensions, and application performances of synthesized surfactants with various hydrophobic chain lengths were studied and compared. With the increasing of alkyl chain length, the Cn lactylates exhibited better surface activity along with excellent foaming and emulsificationproperties, and the wettability on paraffin film and stain removal ability on carbon black-stained cloth improved. Moreover, C10 lactylate showed superior antibacterial ability against E. coli, whereas C12 lactylate demonstrated the best wetting property on canvas sheets and the best decontaminability on sebum-soiled cloths. These results showed that the properties of Cn lactylates can be tuned by modifying the chain length.

Renewable non-edible oils derived long chain (C24.1) bio-based zwitterionic surfactant with ultralow interfacial tension between crude oil and formation brine

A new ultra-long chain monounsaturated 4-(N-nervonicamidopropyl-N,N-dimethylammonium) butane sulfonate (NDAS) zwitterionic surfactant with ultralow interfacial tensions was developed through the modification of nervonic acid derived from renewable non-edible seed oils by a simple and effective method. Its structure was characterized by ESI-HRMS, 1H NMR, and 13C NMR. NDAS surfactant exhibited a strong interfacial activity (∼10−4 mN/m) between the crude oil and the formation brine at a very low surfactant dosage (0.05 g/L) and at high salinity conditions, which is equivalent to 2% (w/w) of dosage of the most traditional surfactants used in the enhanced oil recovery field. Meanwhile, at a very low concentration (0.05 g/L), NDAS demonstrated strong NaCl compatibility up to 100 g/L, Ca2+ ions compatibility up to 200 mg/L, and temperature stability up to 90 °C. The surface tension, emulsification, and biodegradability parameters were also evaluated. This work consolidates our hypothesis that increasing the hydrophobic chain length of a surfactant certainly contributes to the high interfacial activity and good compatibility of salts and temperatures. Hence, it will facilitate the design of a sustainable alternative to petroleum-based chemicals to develop bio-based surfactants and extend the domain of bio-based surfactants to new applications such as in enhanced oil recovery (EOR).