Class Of Surfactants Research Articles

Functional human iPSC-derived alveolar-like cells cultured in a miniaturized 96\u2011Transwell air\u2013liquid interface model

In order to circumvent the limited access and donor variability of human primary alveolar cells, directed differentiation of human pluripotent stem cells (hiPSCs) into alveolar-like cells, provides a promising tool for respiratory disease modeling and drug discovery assays. In this work, a unique, miniaturized 96-Transwell microplate system is described where hiPSC-derived alveolar-like cells were cultured at an air–liquid interface (ALI). To this end, hiPSCs were differentiated into lung epithelial progenitor cells (LPCs) and subsequently matured into a functional alveolar type 2 (AT2)-like epithelium with monolayer-like morphology. AT2-like cells cultured at the physiological ALI conditions displayed characteristics of AT2 cells with classical alveolar surfactant protein expressions and lamellar-body like structures. The integrity of the epithelial barriers between the AT2-like cells was confirmed by applying a custom-made device for 96-parallelized transepithelial electric resistance (TEER) measurements. In order to generate an IPF disease-like phenotype in vitro, the functional AT2-like cells were stimulated with cytokines and growth factors present in the alveolar tissue of IPF patients. The cytokines stimulated the secretion of pro-fibrotic biomarker proteins both on the mRNA (messenger ribonucleic acid) and protein level. Thus, the hiPSC-derived and cellular model system enables the recapitulation of certain IPF hallmarks, while paving the route towards a miniaturized medium throughput approach of pharmaceutical drug discovery.

Novel non-ionic surfactants synthesised through the reaction of CO2 with long alkyl chain epoxides

Two long alkyl chain cyclic carbonates, 1,2-hexadecene carbonate (HDC) and 1,2-dodecene carbonate (DDC), were synthesised via a green catalytic approach from CO2 and the corresponding epoxide, achieving nearly complete conversion with full selectivity. After purification, the two cyclic carbonate products were studied for application as non-ionic surfactants through different tests, including interfacial tension, emulsion stability and droplet size measurements. HDC demonstrated to be suitable for application as a non-ionic surfactant, as it was able to reduce the interfacial tension between water and hexane in an inverse emulsion (i.e. water-in-oil, w/o) at different HDC concentrations (0.5–2.5 wt.%). HDC allowed reaching a similar surface activity compared to a benchmark surfactant as sodium dodecyl sulphate (SDS), although the latter for an oil-in-water (o/w) emulsion, in the concentration range from 1.5 to 2.5 wt.%. On the other hand, DDC was not an efficient emulsion stabiliser, yielding only a slight decrease in the interfacial tension when compared to the results obtained with HDC under the same conditions. This underlined the role of the hydrophobicity of the longer alkyl chain in HDC on the performance of these carbonates as surfactants. For HDC, the optimum ratio of water to hexane for preparing an inverse emulsion was 50/50 vol %, which showed the highest colloidal stability at 2.0 % (w/v) concentration of the surfactant. Increasing the HDC concentration from 1.0 to 2.0 % (w/v) resulted in a significant decrease in average droplet size from 170 to 72 nm, in addition to a decrease in the droplet polydispersity of the dispersion. A further decrease in droplet size and a narrowing in the size distribution, leading to nearly monodisperse nanoemulsions, was achieved upon the addition of CaCl2. The combination of the results obtained in this study reveals a new, promising class of sustainable surfactants consisting of long alkyl chain cyclic carbonates synthesised from CO2.

Molecular Recognition Driven Bioinspired Directional Supramolecular Assembly of Amphiphilic (Macro)molecules and Proteins.

Bioinspired self-assembly has been explored with diverse synthetic scaffolds, among which amphiphiles are perhaps the most extensively studied systems. Classical surfactants or amphiphilic block copolymers, depending on the hydrophobic-hydrophilic balance, produce distinct nanostructures, which hold promise for applications ranging from biology to materials sciences. Nevertheless, their immiscibility-driven aggregation does not provide the opportunity to precisely regulate the internal order, morphology, or functional group display, which is highly desirable, especially in the context of biological applications.A new class of amphiphiles have emerged in the recent past in which the hydrophilic segment(s) is appended with a hydrophobic supramolecular-structure-directing-unit (SSDU), consisting of a π-conjugated chromophore and a H-bonding group. Self-recognition of the SSDU by attractive directional interactions governs the supramolecular assembly, which is fundamentally different than the repulsive solvent-immiscibility driven aggregation of traditional amphiphiles. Such SSDU-appended hydrophilic polymers exhibit entropy-driven highly stable self-assembly producing distinct nanostructures depending on the H-bonding functional group. For example, polymers with the hydrazide-functionalized SSDU attached form a polymersome, while in a sharp contrast, the same polymers when connected to an amide containing SSDU produce a cylindrical micelle via a spherical-micelle intermediate. This relationship holds true for a series of SSDU-attached hydrophilic polymers irrespective of the hydrophobic/hydrophilic balance or chemical structure, indicating that the supramolecular-assembly is primarily controlled by the specific molecular-recognition motif of the SSDU, instead of the packing parameter-based norms. Beyond synthetic polymers, SSDU-attached proteins also exhibit similar molecular-recognition driven self-assembly as well as coassembly with SSDU-attached polymers or hydrophilic wedges, producing multi-stimuli-responsive nanostructures in which the protein gains remarkable protection from thermal denaturation or enzymatic hydrolysis and exhibits redox-responsive enzymatic activity.Furthermore, SSDU-derived bola-shape π-amphiphiles have been recognized as a useful scaffold for the synthesis of unsymmetric polymersomes, rarely reported in the literature. The building block consists of a hydrophobic naphthalene-diimide (NDI) π-system attached to a hydrophilic functional group (ionic or nonionic) and a nonionic wedge on its two opposite arms. Extended H-bonding among the hydrazide groups, placed only on one side of the central chromophore by design, ensures stacking of the NDIs with parallel orientation and induces a preferred direction of curvature so that the H-bonded chain and consequently the functional groups attached to the same side remain at the inner-wall of the supramolecular polymersome. Automatically, the functional groups, located on the other side, are displayed at the outer surface. This design works for different amphiphiles, which by virtue of efficient and predictable functional group display, strongly influences the multivalent binding with different biological targets resulting in efficient enzyme inhibition, glycocluster effect, or antibacterial activity, depending on the nature of the functional group. By taking advantage of the electron accepting nature of the NDI, electron rich pyrene-containing amphiphiles can be costacked in alternating sequence, producing temperature and redox-responsive supramolecular polymers with NDI/pyrene stoichiometry-dependent morphology, lower critical solution temperature (LCST), functional group display, and antibacterial activity.

Phase Behavior of Non‐Ionic Surfactant‐Medium Chain Triglyceride‐Water Microemulsion Systems

AbstractMicroemulsion systems have garnered tremendous interest in the pharmaceutical sector for a variety of drug delivery applications. Non‐ionic surfactants are often the preferred surfactant class given their uncharged nature, enhanced oral safety profile, and generally regarded as safe status as compared to other surfactant classes (Myers, Surfactant science and technology, 2005, p. 29), (Malmsten, Handbook of microemulsion science and technology, 1999, p. 755), (Grove & Mullertz, Chapter 5‐liquid self‐microemulsifying drug delivery systems, 2007), (Liu et al., Water‐insoluble drug formulation, 2008), (Hauss, Advanced Drug Delivery Reviews, 2007, 59, pp. 667–676), (Balazs, Solubility, delivery and ADME problems of drugs and drug‐candidates, 2011, p. 68). In this work, the phase behavior and microemulsion formation potential of four commonly used non‐ionic surfactants, PEG‐40 hydrogenated castor oil, Poloxamer 188, Polysorbate 80, and d‐α‐tocopherol polyethylene glycol succinate were studied via ternary phase diagram (TPD) mapping using a medium chain triglyceride, Miglyol 812. Results indicated notable differences in phase behavior despite similarities in hydrophilic–lipophilic balance value (13–15). All surfactants produced Winsor Type I, oil‐in‐water microemulsions at water concentrations above 40% wt/wt. Winsor Type II water‐in‐oil microemulsions were difficult to obtain even at high oil concentrations of ≥70% wt/wt. Winsor III microemulsions, though rare, were generally obtained in the middle regions of the TPD between 10% and 30% wt/wt water while Winsor IV microemulsions dominated at high surfactant concentrations of ≥45% wt/wt. Opaque emulsion areas were particularly notable in wax state surfactants. Polysorbate 80 and PEG‐40 hydrogenated castor oil demonstrated a high degree of synergism as well as the largest oil‐in‐water (o/w) and water‐in‐oil (w/o) microemulsion formation potential rendering them suitable for a number of enteral and parenteral applications.

PH-switchable pickering emulsions stabilized by polyelectrolyte-biosurfactant complex coacervate colloids

HypothesisPolyelectrolyte-surfactant complexes (PESCs) have long been employed as oil-in-water (o/w) emulsions stabilizers, but never in the structure of colloidal complex coacervates providing a Pickering effect. The complexed state of PESCs could make them unsuitable o/w Pickering emulsifiers, which instead require a balance between colloidal structure and stability, amphiphilicity and wettability. Here we hypothesize that PESCs coacervates are efficient Pickering stabilizers. Instead of classical surfactants, we employ sophorolipid (SL) biosurfactants, atypical anionic/neutral stimuli-responsive biosurfactants. Despite their tunable charge and mild amphiphilic character, they can be used in combination with cationic/neutral polyelectrolytes (chitosan, CHL, or poly-l-lysine, PLL) to form PESC coacervates for the development of biobased, but also pH-switchable, Pickering emulsions. ExperimentsAqueous solutions of SL-CHL (or SL-PLL) complex coacervates are emulsified with dodecane. Confocal laser scanning microscopy (CLSM) and scanning electron microscopy under cryogenic conditions (cryo-SEM) demonstrate the Pickering effect, while optical microscopy and oscillatory rheology respectively assess the emulsion formation and relative viscoelastic properties. FindingsBoth SL-CHL and SL-PLL PESCs stabilize o/w emulsions up to Φoil of 0.7 only in the pH region of complex coacervation (6 < pH < 9): outside this range, phase separation occurs. Rheology shows a typical solid-like response and mechanical recovery upon applying large deformations. CLSM and cryo-SEM highlight a colloidal structure, associated to the complex coacervates, of the oil/water interface and suggest a Pickering effect. These findings demonstrate the Pickering effect from PESC coacervates and the possibility to use biobased and biocompatible components, with application potential in cosmetics, food science, or oil recovery.

Amphiphilic conjugates of ferrocene with amino acids and peptides: Design, synthesis, and studies on their aggregation behavior.

A new class of ferrocenyl surfactants based on covalent linkage between amino acids or peptides and ferrocene was designed. Accordingly, five ferrocenyl amphiphiles, FcS1-5, were synthesized, and their aggregation behaviors in aqueous solutions were studied. Compared to the other surfactants containing ferrocenyl units, FcS have a relatively smaller size and low molecular weight and are easy to synthesize. The influences of the number of carboxylic acid head groups and the number of Fc group in the hydrophobic tail, on the stability and aggregation behavior of these amphiphiles in aqueous medium, were explored to deduce the structure property relationships. A combination of fluorescence and dynamic light scattering techniques was used to elucidate the behavior of these molecules. A good agreement between the results obtained using different techniques was observed.

α‐Sulfo Fatty Methyl Ester Sulfonate: A Review on Chemistry, Processing Technologies, Performance, and Applications in Laundry Detergents

Abstractα‐Sulfo fatty methyl ester sulfonate (α‐MES) is one of the anionic surfactants that is currently used commercially in the cleaning industry. Although the fundamental studies on α‐MES were initiated as far back as the 1950s, it was only recognized as a class of surfactant in the 1980s. In the initial stage of development, α‐MES has been associated with many technical impediments, which created a fear factor for the detergent industry to consider this oleo‐based anionic surfactant for commercial production. However, all the technical adversities have been resolved after five decades of continuous active research and development activities. This paper will review the history, chemistry, process development, processing technologies, performance, commercial production, and applications of oleo‐based based α‐MES with special emphasis on palm oil‐based α‐MES. The paper also will highlight the challenges and adversities faced by the technology developers and product formulators toward the commercialization of α‐MES as an active ingredient in the production of powder and liquid laundry detergents.

Ionic Liquid-Based Surfactants: Recent Advances in Their Syntheses, Solution Properties, and Applications.

The impetus for the expanding interest in ionic liquids (ILs) is their favorable properties and important applications. Ionic liquid-based surfactants (ILBSs) carry long-chain hydrophobic tails. Two or more molecules of ILBSs can be joined by covalent bonds leading, e.g., to gemini compounds (GILBSs). This review article focuses on aspects of the chemistry and applications of ILBSs and GILBSs, especially in the last ten years. Data on their adsorption at the interface and micelle formation are relevant for the applications of these surfactants. Therefore, we collected data for 152 ILBSs and 11 biamphiphilic compounds. The head ions of ILBSs are usually heterocyclic (imidazolium, pyridinium, pyrrolidinium, etc.). Most of these head-ions are also present in the reported 53 GILBSs. Where possible, we correlate the adsorption/micellar properties of the surfactants with their molecular structures, in particular, the number of carbon atoms present in the hydrocarbon “tail”. The use of ILBSs as templates for the fabrication of mesoporous nanoparticles enables better control of particle porosity and size, hence increasing their usefulness. ILs and ILBSs form thermodynamically stable water/oil and oil/water microemulsions. These were employed as templates for (radical) polymerization reactions, where the monomer is the “oil” component. The formed polymer nanoparticles can be further stabilized against aggregation by using a functionalized ILBS that is co-polymerized with the monomers. In addition to updating the literature on the subject, we hope that this review highlights the versatility and hence the potential applications of these classes of surfactants in several fields, including synthesis, catalysis, polymers, decontamination, and drug delivery.

Surface and Biocidal Properties of Gemini Cationic Surfactants Based on Propoxylated 1,6‐Diaminohexane and Alkyl Bromides

AbstractTwo new classes of gemini cationic surfactants—hexanediyl‐1,6‐bis[(isopropylol) alkylammonium] dibromide {in the abbreviation form: CnC6Cn[iPr‐OH] and CnC6Cn[iPr‐OH]2; alkyl: CnH2n + 1 with n = 9, 10, 12 and 14}—have been synthesized by interaction of alkyl bromides with N,N′‐di‐(isopropylol)‐1,6‐diaminohexane and N,N,N′,N′‐tetra‐(isopropylol)‐1,6‐diaminohexane. The surface tension, electrical conductivity, and dynamic light scattering (DLS) techniques were used to investigate the aggregation properties of the gemini cationic surfactants in aqueous solution. The formation of critical aggregates at two concentrations in an aqueous solution from obtained gemini cationic surfactants were determined via the tensiometric method. Thus, these gemini cationic surfactants start to form aggregates at concentrations well below their critical micelle concentrations (CMC). The surface properties and the binding degree (β) of the opposite ion were tested against the length of the surfactant hydrocarbon chain and the number of the isopropylol groups in the head group. By applying the DLS technique, it was explored that how the number of isopropylol groups in gemini cationic surfactants with C12H25 chain affects the sizes of micelles at concentrations greater than CMC. It was discovered that the obtained gemini cationic surfactants have a biocidal character.

Overview

It is an indisputable observation, beyond climate change: that the urgent development of simple new technologies, to ensure the supply of quality fresh water for cities and towns, industry and agriculture, presents an existential challenge for humanity.&#x0D; Several novel technologies that fill that need show that the job is not impossible. They are summarized in this volume. They are environmentally friendly and inexpensive.&#x0D; They include techniques for seawater desalination, wastewater sterilization –including viruses-, selective removal of heavy metals from industrial wastewater, efficient concentration of wastewater slimes to recycle water, and the prevention of water cavitation for much cheaper transport. Other new techniques like high temperature reactions achieved in low temperature water, and low energy desalination are in the wings. Borrowing from biology , new and edible class of surfactants is environmentally friendly, and can replace standard surfactants in present useage. The new technologies are cheap and scalable.

Synthesis and Characterization of a Novel Class of Zwitterionic Fluorocarbon Surfactants Based on Perfluorobutyl

Abstract Perfluorooctane sulfonate (PFOS) and its derivatives had been banned due to their potential environmental hazards, although they possessed excellent surface activity. An effective method to solve this problem was to shorten the fluorocarbon chain of these surfactants from C°H17 to C4F9. As previous studies had shown, zwitterionic surfactants possess higher surface activity but have lower toxicity compared to other types of surfactants. In view of this, a class of novel zwitterionic fluorocarbon surfactants (n-CFNA-Br) with perfluorobutyl moiety was synthesized in this work. Their structures were characterized by FTIR, 1H NMR, 13C NMR, 19F NMR and MS. The results showed that all synthesized n-CFNA-Br had almost the same minimum surface tension, but their critical micelle concentration (CMC) decreased with increasing length of hydrophobic carbon chain. In pure water, the surface tension at the CMC (γCMC) of the four n-CFNA-Br were about 20 mN/m, and the CMC values were 7.73 mmol/L for 1-CFNA-Br, 4.70 mmol/L for 2-CFNA-Br, 4.13 mmol/L for 3-CFNA-Br, and 3.36 mmol/L for 4-CFNA-Br, indicating high efficiency and effectiveness. In 0.1 mol/L NaCl, the CMC values reduced to less than half of the CMC values measured in the pure aqueous surfactant solution, while the surface tensions γCMC remained almost unchanged, indicating good salinity tolerance of the synthesized surfactants. The acidic surfactant solutions exhibited similar CMC values to the saline solutions, but the surface tension γCMC increased slightly to 25 mN/m. However, further investigation showed that the n-CFNA-Br surfactants exhibited poor surface activity in alkaline solution (0.1 mol/L NaOH). In the pH range of 6.6 to 10.4, white precipitates appeared in the surfactant solutions after some time, indicating that the n-CFNA-Br are not suitable for use in alkaline systems with pH greater than 6.6.

A Review on Recent Progress of Glycan-Based Surfactant Micelles as Nanoreactor Systems for Chemical Synthesis Applications

The nanoreactor concept and its application as a modality to carry out chemical reactions in confined and compartmentalized structures continues to receive increasing attention. Micelle-based nanoreactors derived from various classes of surfactant demonstrate outstanding potential for chemical synthesis. Polysaccharide (glycan-based) surfactants are an emerging class of biodegradable, non-toxic, and sustainable alternatives over conventional surfactant systems. The unique structure of glycan-based surfactants and their micellar structures provide a nanoenvironment that differs from that of the bulk solution, and supported by chemical reactions with uniquely different reaction rates and mechanisms. In this review, the aggregation of glycan-based surfactants to afford micelles and their utility for the synthesis of selected classes of reactions by the nanoreactor technique is discussed. Glycan-based surfactants are ecofriendly and promising surfactants over conventional synthetic analogues. This contribution aims to highlight recent developments in the field of glycan-based surfactants that are relevant to nanoreactors, along with future opportunities for research. In turn, coverage of research for glycan-based surfactants in nanoreactor assemblies with tailored volume and functionality is anticipated to motivate advanced research for the synthesis of diverse chemical species.

Synthesis, characterization, and functional evaluation of branched dodecyl phenol polyoxyethylene ethers: a novel class of surfactants with excellent wetting properties.

A series of branched dodecyl phenol polyoxyethylene ethers (b-DPEOn) were successfully synthesized via alkylation and ethylene oxide addition reactions. The alkylation reaction was conducted by using a branched internal olefin as the raw material. Furthermore, the conversion rate of the branched dodecene was measured to be 98.1% and the selectivity towards branched dodecyl phenol (b-DP) was 95.9%. Moreover, b-DPEOn (b-DPEO7, b-DPEO10, b-DPEO12) were obtained via the reaction of ethylene oxide with b-DP. Notably, b-DPEO10 can efficiently reduce the surface tension of water below 31.55 mN m−1 at the critical micelle concentration (cmc) and the cmc value in water was approximately 1.3 × 10−2 g L−1 at 25 °C. The preferable wetting ability of b-DPEO10 was superior to that of commercialized dodecyl phenol polyoxyethylene ether (c-DPEOn), so it will be promoted and used in the textile and pesticide industries.

К ВОПРОСУ ОБ ЭКОТОКСИЧНОСТИ И ЭФФЕКТИВНОСТИ РАЗЛИЧНЫХ КЛАССОВ ПРОМЫШЛЕННЫХ НЕИОНОГЕННЫХ ПАВ, ИСПОЛЬЗУЕМЫХ ПРИ ОЧИСТКЕ МЕТАЛЛИЧЕСКИХ ПОВЕРХНОСТЕЙ В ПРОЦЕССЕ КАПИЛЛЯРНОГО КОНТРОЛЯ ДЕТАЛЕЙ АВИАЦИОННОЙ ТЕХНИКИ (обзор)

A review of modern classes of nonionic surfactants used for cleaning metal surfaces is carried out. The following aspects are considered: efficiency of cleaning metal surfaces, ecotoxicity, biodegradability, impact on human health. The most promising class of surfactants – alkyl polyglycosides (APG) – for cleaning metal surfaces, including in the process of capillary control, has been determined. It is noted that APGs have shown high efficiency in removing even such contaminants as denatured protein and burnt corn starch from metal surfaces. In addition, APGs have the highest emulsifying ability among industrial surfactants, which effectively affects the reduction in surfactant consumption when cleaning the surfaces.

Comparative study of saponin for surfactant properties and potential application in personal care products

Surfactants are typically organic compounds containing hydrophobic and hydrophilic groups bearing polar and non-polar classes. Saponin is one of the surfactant classes present in the plant species with steroidal aglycone or triterpenoid and one or more chains of sugar characterized by its structure. Now days, consumers are becoming more aware of natural products associated with their physicochemical properties. Saponin's potential use as surfactant is caused by the combination of a non-polar sapogenin side chain and a water-soluble one, which is close to the structure of most lipophilic and hydrophilic molecular sections of synthetic surfactants. The foaming power of the 0.6% crude saponins solution, 0.6% SLS solution and 0.6% Tween 80 solution were found to be 80%, 93.87% and 97.56% respectively. It showed that 0.6% crude saponins possessed moderate foaming ability. The surface active properties of saponin were also compared with the synthetic surfactants such as sodium lauryl sulfate (SLS) and Tween 80. Surface tension of 0.6% solution of saponin, SLS and Tween 80 was determined as 37.39 mN/m, 26.15 mN/m and 37.18 mN /m respectively. Critical micelle concentration (CMC) values of saponin and Tween 80 was comparable.

Structural and dynamical properties of water in surfactant-like peptide-based nanotubes: Effect of pore size, tube length and charge

Atomistic molecular dynamics simulations were carried out to study the structural and dynamical properties of water molecules around pre-assembled surfactant-like peptide (SLP) nanotubes in aqueous media. These SLPs can be thought as a class of biocompatible and biodegradable surfactants for biomedical applications. Nanotube-like structures were considered where glycine and lysine (G6K) are taken as the constituents for the composition of the SLPs. The nanotubes considered were of different dimensions; such as 18 × 15 (number of peptides on the circumference x number of peptides layers), 18 × 12 and 16 × 12 for both charged and neutral analogues. The charged composition consists of protonated nitrogen in the lysine subunit and chlorine/bromine as counter ions. It is found that the neutral SLPs have less hydrated inner core consisting of more tetrahedral water compared to their charged analogues. The hydrogen bond lifetime of water-water and water-peptide molecules increases in the inner pore and found to be maximum for charged 16 × 12 system. Outside the pore, charged analogue of 18 × 15 have more water-water hydrogen bond lifetime compared to all other systems. However, protein-water hydrogen bond lifetime was found to be more for neutral analogues outside the pore due to more probable interactions of SLPs with water molecules.

Chemoenzymatic Synthesis of New Aromatic Esters of Mono- and Oligosaccharides

An efficient and convenient chemoenzymatic route for the synthesis of novel phenolic mono-, di- and oligosaccharide esters is described. Acetal derivatives of glucose, sucrose, lactose and inulin were obtained by chemical synthesis. The fully characterized pure sugar acetals were subjected to enzymatic esterification with 3-(4-hydroxyphenyl) propionic acid (HPPA) in the presence of Novozyme 435 lipase as a biocatalyst. The aromatic esters of alkyl glycosides and glucose acetal were obtained with good esterification yields, characterized by mass spectrometry (MALDI-TOF MS), infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (1H NMR, 13C NMR). The synthesis of aromatic esters of disaccharide acetals was successful only for the enzymatic esterification of sucrose acetal. The new chemoenzymatic route allowed the synthesis of novel aromatic esters of inulin as the inulin monoacetal monoester and diester and the inulin diacetal monoester with a polymerization degree of two, as well as the inulin monoacetal monoester with a degree of polymerization of three, were obtained by enzymatic acylation of inulin acetals with HPPA. These compounds could represent a new class of sugar ester surfactants with enhanced bioactivity, antioxidative and antimicrobial properties and with potential application in drug delivery systems.

Oil-Tolerant Nonionic Worm-like Micellar Solution.

The goal of this work is to study the effect of crude oil on worm-like micelles and identify any oil-tolerant systems. A new class of nonionic surfactants was synthesized that forms viscous worm-like micelles under a wide range of temperature and salinity conditions. Aqueous stability, rheology, cryogenic transmission electron microscopy imaging, and dynamic-light-scattering measurements were performed to understand properties, shape, and size of the micelles formed using these surfactants under different temperatures and salinity conditions and in the presence of hydrocarbons. These micellar solutions maintained high viscosity in the presence of small amounts (up to 8 vol %) of crude oils and pure hydrocarbons. Similar experiments were performed with conventional surfactant systems that were known to form worm-like micelles; they did not show oil tolerance. Larger alkanes and viscous crude oils affect the viscosity and transformation of cylindrical micelles less. These new surfactants are useful for oil and gas operations such as hydraulic fracturing, conformance control, and mobility control as they form viscous worm-like micelles in the presence of small amounts of crude oils.

Wettability alteration and oil recovery by surfactant assisted low salinity water in carbonate rock: The impact of nonionic/anionic surfactants

Combining low salinity water (LSW) and chemicals to enhance oil recovery has recently received more attention in the oil industry. In this study, a systematic experimental procedure was conducted to evaluate the performance of low salinity nonionic surfactant with/without anionic surfactant in wettability alteration and oil recovery of oil-wet carbonate having high salinity formation water (FW) (196 g/L) and moderate temperature (75 °C). A polyethoxylated nonionic surfactant (C13EO12) and two anionic surfactants: sulfonate (IOS 20–24) and carboxylate (AEC 938) were used in this study. Contact angle (CA) results showed that low salinity nonionic surfactant was effective in altering the wettability of oil-wet calcite toward water-wet state. While the low salinity anionic surfactants' systems were only able to reduce the oil-wetness of the oil-wet calcite. When nonionic surfactant is mixed with anionic surfactant, the wettability of oil-wet calcite was altered toward intermediate-wet or only a reduction of its oil-wetness occurred depending on the type of the anionic surfactant. Spontaneous imbibition tests using oil-wet limestone cores showed that among the low salinity single surfactants’ systems, carboxylate anionic surfactant resulted in the highest oil recovery (61% of oil initially in place (OIIP)) and sulfonate anionic surfactant resulted in the lowest oil recovery (31% of OIIP). The low salinity nonionic surfactant recovered 51% of OIIP by spontaneous imbibition. Addition of sulfonate anionic surfactant to the nonionic surfactant resulted in an oil recovery of 49% of OIIP while addition of carboxylate anionic surfactant to the nonionic surfactant considerably improved the oil recovery to 74% of OIIP. Hence, selection of proper surfactant class is crucial for a successful oil recovery.

α-Sulfo alkyl ester surfactants: Impact of changing the alkyl chain length on the adsorption, mixing properties and response to electrolytes of the tetradecanoate

Hypothesis: The α-sulfo alkyl ester, AES, surfactants are a class of anionic surfactants which have potential for improved sustainable performance in a range of applications, and an important feature is their enhanced tolerance to precipitation in the presence of multivalent counterions. It is proposed that their adsorption properties can be adjusted substantially by changing the length of the shorter alkyl chain, that of the alkanol group in the ester.Experiments: Surface tension and neutron reflectivity have been used to investigate the variation in the adsorption properties with the shorter alkyl chain length (methyl, ethyl and propyl), the impact of NaCl on the adsorption, the tendency to form surface multilayer structures in the presence of AlCl3, and the effects of mixing the methyl ester sulfonate with the ethyl and propyl ester sulfonates on the adsorption.Findings: The variations in the critical micelle concentration, CMC, the adsorption isotherms, the saturation adsorption values, and the impact of NaCl illustrate the subtle influence of varying the shorter alkyl chain length of the surfactant. The non-ideal mixing of pairs of AES surfactants with different alkanol group lengths of the ester show that the extent of the non-ideality changes as the difference in the alkanol length increases. The surface multilayer formation observed in the presence of AlCl3 varies in a complex manner with the length of the short chain and for mixtures of surfactants with different chains lengths.