Aliphatic Surfactants Research Articles

Solubilization of Carbon Nanobelts in Aqueous Solutions: Optical and Colloidal Properties.

Carbon nanobelts (CNBs) correspond to carbon nanotube (CNT) segments and are insoluble in most common aqueous solutions, posing challenges across diverse applications. In this study, [12] CNB, which corresponds to a (6,6) CNT segment, was solubilized by aliphatic surfactant micelles through host-guest complexation, which was confirmed by comprehensive analyses involving spectrophotometry, mass spectrometry, and molecular dynamics simulations. Through this solubilization, zero-Stokes shift emission of the CNB could occur, which could be ascribed to the symmetry-allowed transition. In contrast, CNB was insoluble in non-aliphatic surfactant solutions. The mechanism by which CNB is solubilized using aliphatic surfactants is completely distinct from that of the CNT dispersion mechanism. The present finding provides knowledge of the effectiveness of aliphatic compounds in solubilizing CNBs and their derivatives (carbon nanohoops), which show significant potential for various applications in aqueous systems, including biological applications.

Structuring liquids through solvent-assisted interfacial association of oppositely charged polyelectrolytes and amphiphiles

HypothesisSculpting liquids into different shapes is usually based on the interfacial interactions of functionalized nanoparticles or polymers with specific ligands, leading to exciting material properties due to the combination of the mobility of liquid components with the solid-like characteristic of the arrested liquid/liquid interface. There is an intense interest in novel structured liquids produced from simple compounds with versatile application potentials. Complexes of oppositely charged commercial polyelectrolytes and traditional aliphatic surfactants are good candidates for this goal since they reveal rich structural features and could adsorb at various interfaces. However, they have not been applied yet for structuring liquids. ExperimentsThe interfacial interactions and film formation between aqueous sodium poly(styrene) sulfonate solutions (NaPSS) and hexadecylamine (HDA) solutions in various alkanols were investigated by surface tension measurements and ATR-IR spectroscopy. 3D printing experiments also assessed the robustness of the formed films. FindingsArrested fatty alcohol/water interfaces were formed due to the interfacial association of NaPSS, HDA, and alkanol molecules, which also act as cosurfactants in the surface region. These solid films enable the synthesis of temperature-sensitive all-in-liquid constructs and offer alternatives to bulk polyion/mixed surfactant assemblies prepared earlier through numerous synthesis steps.

A guide to designing graphene-philic surfactants

HypothesisAs compared to common aliphatic surfactants, increasing the number of pendant or incorporated aromatic groups in a surfactant is expected to offer significant enhancement in the affinity for graphene surfaces. The basis for enhanced graphene-philicity of aromatic surfactants is that they can develop appreciable π – π interactions with graphene. Furthermore, charged (anionic) surfactants are expected to confer electrostatic stabilization on surfactant-graphene composites. Hence, it is expected that anionic aromatic surfactants combine these two properties for effective stabilization of graphene dispersions in water. ExperimentalThe properties of two custom made graphene-compatible surfactants carrying two and three aromatic moieties in the hydrophobic tails, namely DC3Ph2 (sodium 1,4-dioxo-1,4-bis(3-phenylpropoxy)butane-2-sulfonate) and TC3Ph3 (sodium 1,5-dioxo-1,5-bis(3-phenylpropoxy)-3-((3-phenylpropoxy)carbonyl) pentane-2-sulfonate) were compared with other common ionic commercial surfactants. Air-water (a/w) surface tension measurements were used to assess the surfactant adsorption and interfacial packing in the absence and presence of graphene. The surfactant coverage index for graphene (Ф) was calculated using surfactant headgroup areas derived from a/w surface tension data, chain volumes, and molecular fragment volumes from literature. FindingsIncreasing the number of aromatic groups and tails per surfactant was shown to increase the ability of surfactants to pack and fill space, as expressed by Ф. Comparison between the values of Ф for surfactants of different chain structure and architecture showed that the affinity for graphene increased with Ф. Hence, there is an implicit link between surfactant-graphene compatibility and the identity, chemical composition and architecture of the surfactant chains.

Surface activity and thermodynamic properties of some green surfactants from wastes in formation water at reservoir conditions

In this work an attention has been paid to prepare some anionic and nonionic surfactants based on aliphatic and aromatic moieties to evaluate their application in enhanced oil recovery (EOR). The aliphatic surfactants derived from Jatropha and waste cooking oil but the aromatics derived from alkyl benzene sulfonic acid. The nonionic surfactants were prepared by tans esterification of acids with different types of poly ethylene glycols and anionic surfactants prepared by saponification. The designated formula of the aromatic surfactants was RC6H4SO3 (en)x OH and RΦSO3Na where aliphatic surfactants designated as RCOO(en)n OH and RCOONa. The structures of these surfactants were confirmed by FT-IR. The surface activity and thermodynamic properties for three surfactants groups have been investigated. The Surface and interfacial tension were measured in high salinity formation water (200,000ppm) at different temperatures (25, 35, 45 and 55 °C) and 1000 psi. From surface tension measurements, CMC, Πcmc, Γmax, Amin, Pc20 were calculated. The thermodynamic parameters of micellization and adsorption were also calculated. The data discussed on the basis of structural effect. The EHJ23 (RCOO(en)23OH) gave a high value of structural effect(22.18 KJmol−1) which met the most negative value of ΔGads (-37.61 KJmol−1) . The results explained that the (ΔGads) negatives values were more than the values of (ΔΔGmic), which means that surfactants prefer to adsorb at interface before forming micelles. These surfactants exhibited ultra-low interfacial tension (IFT) at 55 °C and 1000 psi between 8 × 10−2 to 2 × 10−4 mNm−1 which gave indication that, these surfactants can be used in EOR applications.

Application of the easy concentration effect in concrete technology

The results of studies of the influence of nano-modifiers on the appearance of dimmers of colloidal surfactants on the compressive strength of concrete and the rate of its formation are presented. It has been shown that colloidal aliphatic surfactant increases the strength of concrete. Moreover, the joint introduction of a colloidal aliphatic surfactant and traditional hydrophilic surfactants leads to an even greater increase in the strength of concrete. A significant increase in concrete strength occurs at an early age in concrete.

Polymerization-Driven Hierarchical Co-Assembly of Micelles for Access to Mesoporous Hollow Metal Coordination Bio-Polymers

Bio-inspired hierarchical self-assembly provides elegant and powerful bottom-up strategies for the creation of complex materials. However, the current self-assembly approaches for natural bio-compounds often result in materials with limited diversity and complexity in architecture as well as microstructure. Here, we develop a novel coordination polymerization-driven hierarchical assembly of micelle strategy, using phytic acid-based natural compounds as an example, for the spatially controlled fabrication of metal coordination bio-polymers. The aliphatic surfactant pentadecafluorooctanoic acid and block co-polymer of polystyrene-b-poly (ethylene oxide) are assembled into two kinds of the discrete amphiphilic micelles. They evolve into hollow vesicles surrounding with spherical micelles, driven by the strong interaction triggered by coordination polymerization of ferric phytate precursors, which in turn facilitate the growth of precursors in a confined space. Consequently, the synchronous control on morphology and mesoscale structure for bio-compounds was successfully achieved for the first time. The resultant ferric phytate bio-polymer nanospheres feature hollow architecture, ordered meso-channels of ~12 nm, high surface area of 401 m2g-1, and large pore volume of 0.53 cm3g-1. As an advanced anode material, this bio-derivative metal coordination polymer delivers a remarkable reversible capacity of 540 mAh g-1 at 50 mA g-1, good rate capability and cycling stability for the use in sodium ion batteries. This study holds great potential of the design of new complex bio-materials with supramolecular chemistry.

Metal Free Acid‐Mediated Solid‐State Polymerization and Processability of Polymers Based on 3,4‐Alkylenedioxythiophenes

ABSTRACTThe present article reports metal free acid‐mediated polymerization of 3,4‐alkylenedioxythiophenes in a solvent free medium and processability of insoluble polymers. It also describes structural variants and functional aqueous dispersions based on 3,4‐alkylenedioxythiophenes. Polymers were processed by dispersing the insoluble polymer powders in aqueous media using polymeric aromatic surfactant (polystyrenesulfonate, PSS) and aliphatic surfactant (sodiumdodecylsulfonate, SDS), respectively. The effect of surfactant on particle size, stability, and conductivity of the dispersions was investigated in detail. Polymer particles in SDS‐based dispersions tend to agglomerate which resulted enhanced conductivity of the thin films. Electrochemical studies revealed that the polymers are electroactive in nature and are transparent in oxidized state. The electrochromic contrast between the oxidized and reduced states of the polymers was in the range of 40–46%. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 783–791

Micellar systems of aliphatic alcohol ethoxylates as a sustainable alternative to extract soybean isoflavones

Ethoxylated aliphatic surfactants belonging to the Genapol and Tergitol series were assessed as extraction systems of isoflavones. They showed good extraction properties when compared with different solvents, the Genapol X-080 exhibiting the best performance. Available commercial isoflavone pills were used, as a starting simple matrix, to determine the parameters that affect the extraction procedure. The temperature and the surfactant concentration showed to be factors that favored significantly the extraction performance. The application of optimized variables (Genapol X-080 11% m/m, pH 4.5; extraction temperature of 54 °C and extraction time of 60 min) on soybean flour (natural) allowed extracting 3.237 ± 0.173 mg of isoflavone per gram of treated flour. This result was three times what it was for methanol under identical conditions. Extraction with these micellar systems represents a sustainable alternative methodology for industrial purposes due to its low cost, biodegradability, non-toxicity and easy scaling up.

Analysis of the Efficiency of Surfactant-Mediated Stabilization Reactions of EGaIn Nanodroplets.

A methodology based on light scattering and spectrophotometry was developed to evaluate the effect of organic surfactants on the size and yield of eutectic gallium/indium (EGaIn) nanodroplets formed in organic solvents by ultrasonication. The process was subsequently applied to systematically evaluate the role of headgroup chemistry as well as polar/apolar interactions of aliphatic surfactant systems on the efficiency of nanodroplet formation. Ethanol was found to be the most effective solvent medium in promoting the formation and stabilization of EGaIn nanodroplets. For the case of thiol-based surfactants in ethanol, the yield of nanodroplet formation increased with the number of carbon atoms in the aliphatic part. In the case of the most effective surfactant system-octadecanethiol-the nanodroplet yield increased by about 370% as compared to pristine ethanol. The rather low overall efficiency of the reaction process along with the incompatibility of surfactant-stabilized EGaIn nanodroplets in nonpolar organic solvents suggests that the stabilization mechanism differs from the established self-assembled monolayer formation process that has been widely observed in nanoparticle formation.

Roles of hydrocarbon chain-length in preparing graphene oxide from mildly-oxidized graphite with intercalating anionic aliphatic surfactants

The longer the length of carbon chain, the higher the yield of graphene oxide prepared.

Effects of Surfactants and Polyelectrolytes on the Interaction between a Negatively Charged Surface and a Hydrophobic Polymer Surface.

We have measured and characterized how three classes of surface-active molecules self-assemble at, and modulate the interfacial forces between, a negatively charged mica surface and a hydrophobic end-grafted polydimethylsiloxane (PDMS) polymer surface in solution. We provide a broad overview of how chemical and structural properties of surfactant molecules result in different self-assembled structures at polymer and mineral surfaces, by studying three characteristic surfactants: (1) an anionic aliphatic surfactant, sodium dodecyl sulfate (SDS), (2) a cationic aliphatic surfactant, myristyltrimethylammonium bromide (MTAB), and (3) a silicone polyelectrolyte with a long-chain PDMS midblock and multiple cationic end groups. Through surface forces apparatus measurements, we show that the separate addition of three surfactants can result in interaction energies ranging from fully attractive to fully repulsive. Specifically, SDS adsorbs at the PDMS surface as a monolayer and modifies the monotonic electrostatic repulsion to a mica surface. MTAB adsorbs at both the PDMS (as a monolayer) and the mica surface (as a monolayer or bilayer), resulting in concentration-dependent interactions, including a long-range electrostatic repulsion, a short-range steric hydration repulsion, and a short-range hydrophobic attraction. The cationic polyelectrolyte adsorbs as a monolayer on the PDMS and causes a long-range electrostatic attraction to mica, which can be modulated to a monotonic repulsion upon further addition of SDS. Therefore, through judicious selection of surfactants, we show how to modify the magnitude and sign of the interaction energy at different separation distances between hydrophobic and hydrophilic surfaces, which govern the static and kinetic stability of colloidal dispersions. Additionally, we demonstrate how the charge density of silicone polyelectrolytes modifies both their self-assembly at polymer interfaces and the robust adhesion of thin PDMS films to target surfaces.

Parallel multifunctionalization of nanoparticles: a one-step modular approach for in vivo imaging.

Multifunctional nanoparticles are usually produced by sequential synthesis, with long multistep protocols. Our study reports a generic modular strategy for the parallel one-step multifunctionalization of different hydrophobic nanoparticles. The method was designed and developed by taking advantage of the natural noncovalent interactions between the fatty acid binding sites of the bovine serum albumin (BSA) and the aliphatic surfactants on different inorganic nanomaterials. As a general example of the approach, three different nanoparticles-iron oxide, upconverting nanophosphors, and gold nanospheres-were nanoemulsified in water with BSA. To support specific applications, multifunctional capability was incorporated with a variety of previously modified BSA modules. These modules include different conjugated groups, such as chelating agents for (68)Ga or (89)Zr and ligand molecules for enhanced in vivo targeting. A large library of 13 multimodal contrast agents was developed with this convergent strategy. This platform allows a highly versatile and easy tailoring option for efficient incorporation of functional groups. Finally, as demonstration of this versatility, a bimodal (PET/MRI) probe including a maleimide-conjugated BSA was selectively synthesized with an RGD peptide for in vivo imaging detection of tumor angiogenesis.

Exploring the role of hydration and confinement in the aggregation of amyloidogenic peptides Aβ(16-22) and Sup35(7-13) in AOT reverse micelles.

Knowledge of how intermolecular interactions of amyloid-forming proteins cause protein aggregation and how those interactions are affected by sequence and solution conditions is essential to our understanding of the onset of many degenerative diseases. Of particular interest is the aggregation of the amyloid-β (Aβ) peptide, linked to Alzheimer's disease, and the aggregation of the Sup35 yeast prion peptide, which resembles the mammalian prion protein linked to spongiform encephalopathies. To facilitate the study of these important peptides, experimentalists have identified small peptide congeners of the full-length proteins that exhibit amyloidogenic behavior, including the KLVFFAE sub-sequence, Aβ16-22, and the GNNQQNY subsequence, Sup357-13. In this study, molecular dynamics simulations were used to examine these peptide fragments encapsulated in reverse micelles (RMs) in order to identify the fundamental principles that govern how sequence and solution environment influence peptide aggregation. Aβ16-22 and Sup357-13 are observed to organize into anti-parallel and parallel β-sheet arrangements. Confinement in the sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles is shown to stabilize extended peptide conformations and enhance peptide aggregation. Substantial fluctuations in the reverse micelle shape are observed, in agreement with earlier studies. Shape fluctuations are found to facilitate peptide solvation through interactions between the peptide and AOT surfactant, including direct interaction between non-polar peptide residues and the aliphatic surfactant tails. Computed amide I IR spectra are compared with experimental spectra and found to reflect changes in the peptide structures induced by confinement in the RM environment. Furthermore, examination of the rotational anisotropy decay of water in the RM demonstrates that the water dynamics are sensitive to the presence of peptide as well as the peptide sequence. Overall, our results demonstrate that the RM is a complex confining environment where substantial direct interaction between the surfactant and peptides plays an important role in determining the resulting ensemble of peptide conformations. By extension the results suggest that similarly complex sequence-dependent interactions may determine conformational ensembles of amyloid-forming peptides in a cellular environment.

Role of Charge and Solvation in the Structure and Dynamics of Alanine-Rich Peptide AKA2 in AOT Reverse Micelles.

The propensity of peptides to form α-helices has been intensely studied using theory, computation, and experiment. Important model peptides for the study of the coil-to-helix transition have been alanine–lysine (AKA) peptides in which the lysine residues are placed on opposite sides of the helix avoiding charge repulsion while enhancing solubility. In this study, the effects of capped versus zwitterionic peptide termini on the secondary structure of alanine-rich peptides in reverse micelles are explored. The reverse micelles are found to undergo substantial shape fluctuations, a property observed in previous studies of AOT reverse micelles in the absence of solvated peptide. The peptides are observed to interact with water, as well as the AOT surfactant, including interactions between the nonpolar residues and the aliphatic surfactant tails. Computation of IR spectra for the amide I band of the peptide allows for direct comparison with experimental spectra. The results demonstrate that capped AKA2 peptides form more stable α helices than zwitterionic AKA2 peptides in reverse micelles. The rotational anisotropy decay of water is found to be distinctly different in the presence or absence of peptide within the reverse micelle, suggesting that the introduction of peptide significantly alters the number of free waters within the reverse micelle nanopool. However, neither the nature of the peptide termini (capped or charged) nor the degree of peptide helicity is found to significantly alter the balance of interactions between the peptides and the environment. Observed changes in the degree of helicity in AKA2 peptides in bulk solution and in reverse micelle environments result from changes in peptide confinement and hydration as well as direct nonpolar and polar interactions with the water–surfactant interface.

Coadsorption of Low-Molecular Weight Aromatic and Aliphatic Alcohols and Acids with the Cationic Surfactant, CTAB, on Silica Surfaces

We have investigated the coadsorption of a range of small molecules with the cationic surfactant CTAB to silica surfaces over a range of concentrations and CTAB to solute ratios and compared the coadsorption with adsorption in the presence of the salicylate ion. We find that molecules with aromatic character and molecules with double bonds are most favorably adsorbed, and we attribute this to cation-π bonding between the surfactant headgroups and the π orbitals of the unsaturated bonds of the solute molecules. The adsorption is complex and depends on chemical interactions between the solute molecules and the surfactant, which are highly specific to the structure of the solute. To improve our understanding of the specifics of these interactions, we have performed one-dimensional rotating frame Overhauser spectroscopy (ROESY) nuclear magnetic resonance experiments. These experiments show the complexity of the intermolecular interactions and can be used to determine the position of the solute molecule with regard to the CTAB molecules in the adsorbed aggregates. The ROESY spectrum for the salicylate anion is distinct from those of the other solute molecules and suggests that the anions are dimerizing. Along with the cation-π bonding between the dimers, this provides a model for the strong influence that salicylate has on adsorption, micellar structure, and viscoelasticity. The ROESY data indicate that the catechol molecule interacts with all parts of the surfactant alkane chains such that they wrap around the molecule, but this has little effect on the interfacial curvature or aggregate shape. More intense isophthalic acid-CTAB intermolecular ROEs compared to those of other aromatic solutes are consistent with an interaction between isophthalic acid and the headgroups of two surfactant molecules that slows the intramicellar motion of isophthalic acid. Differences in interactions between solute molecules and the aliphatic surfactant chains do not result in changes in micelle structure.

Parenteral Hydrocarbon Injection and Associated Toxicities: Two Case Reports

Many cases of hydrocarbon toxicity occur annually due to oral or inhalational exposure. Rarely are hydrocarbons injected subcutaneously or intravenously. These parenteral routes of exposure, however, can have a wide range of consequences ranging from mild skin irritation to tissue necrosis, pulmonary injury, neurologic consequences, cardiovascular collapse, and death. WD-40™ is a commonly used household hydrocarbon containing aliphatic hydrocarbon (45 – 50%), low vapor pressure aliphatic hydrocarbon (12 – 18%), petroleum-based oil (<25%), carbon dioxide (2–3%), surfactant (<2%), and other “non-hazardous ingredients” (<10%).1 We present a pair of cases and associated visual images of complications from intravenous (IV) and subcutaneous (SC) WD-40 injection. Additionally, we will discuss complications from parenteral hydrocarbon exposures, in particular pulmonary injury and local tissue reactions as observed in our cases.

Electropolymerization of pyrrole: Dendrimers, nano-sized patterns and oscillations in potential in presence of aromatic and aliphatic surfactants

Compact, dendritic and featherlike growth morphologies, growth kinetics and electrical conductivity of aggregates obtained during electropolymerization in surfactant added systems (A) pyrrole–dodecyl benzene sulfonic acid (DBSA)–H2O (B) pyrrole–DBSA–sodium dodecyl sulfate (NaDS)–H2O and (C) pyrrole–DBSA–cetyl trimethyl ammonium bromide (CTAB)–H2O were investigated using vertical anode and circular cathode. Effect of time, field intensity, [DBSA], [NaDS] and [pyrrole] were studied for systems A, B, and C. Different transitions are seen in all the systems at different conditions. It is observed that growth is highest in system B. Growth rate follows the sequence B>A>C. Growth kinetics was studied and electric potential oscillations were monitored as a function of time during electropolymerization in systems A–C at different experimental conditions. On addition of NaDS and CTAB, particle size was increased and decreased respectively. Growth rate was found to be increased in system B due to the increase in the anodic charge of the film, leading to the better protonation of polypyrrole and decreased in system C due to coordination of CTAB with the growing polypyrrole chain. The formation of polypyrrole aggregates has been explained on the basis of diffusion limited aggregation (DLA) model. Fractal dimension of a pattern was found to be 1.69, in agreement with DLA model. Electropolymerized aggregates were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric studies (TGs), powder X-ray diffraction (XRD) and electrical conductivity measurements. Nanosized polypyrrole was formed in the range 50–100nm as evident by SEM and TEM studies. During electropolymerization, oscillations in potential were monitored as a function of time at different experimental conditions. Nature of oscillations was periodic.

Effect of organic species on the solar detoxification of water polluted with pesticides

The effect of organic species on a solar-driven photo-Fenton treatment of a mixture of pesticides (methyl-oxydemethon, methidathion, carbaryl and dimethoate) has been studied in this paper. Triethoxyisododecyl alcohol, acetophenone and ethylenediaminetetraacetic acid (EDTA) have been used as examples of surfactants, solvents and complexing agents, respectively. An inhibitory effect on mineralization as well as on the elimination of the pesticides was observed in the case of the aliphatic surfactants, most probably due to the competition between the pesticides and the added organic matter for reaction with the relatively unselective hydroxyl radical. A methodology combining chemical analyses and bioassays was tested in order to explore the applicability of coupling a photo-Fenton process with a biological treatment in the presence of the surfactant. Despite the complexity of the mixture under study, a reliable monitoring of the process was accomplished; the biocompatibility of the mixture was enhanced and the optimal irradiation intensity was achieved just after complete removal of the pesticides.

Controlled stability of a polymer-colloid complex in aqueous-saline solutions

The interaction of a labeled polymethacrylate anion with aliphatic and aromatic cationic surfactants of various structures in aqueous and aqueous-saline solutions has been studied by fluorescent methods. It has been shown that variations in the pH of solution, the concentration of surfactants, the number of methylene groups in an alkyl fragment, and the nature of an amino group may efficiently affect the binding of surfactants by polyanion molecules. A successive and noticeable increase in the stability of complexes after replacement of the tertiary groups of a surfactant with tertiary, secondary, or primary amino groups indicates the significance of the steric fit of charges in ion pairs. This effect may be especially important for designing polymer-colloid systems with controlled stability in aqueous-saline solutions.

Modification of nano-sized layered double hydroxides by long-chain organic aliphatic surfactants

The inter-layer anion of layered double hydroxides (LDH) with a hydrotalcite (HT)-like structure was ion-exchanged with various organic surfactants, particularly with long chain aliphatic surfactants. After the ion-exchange process, the basal spacing of the LDH was increased and the increase of the basal spacing depended on various factors, such as the intercalation capacity functionality and orientation capability of the surfactant. Of the employed surfactants, stearic acid intercalated LDH showed the highest increase of the basal spacing, which was confirmed by XRD analysis. FTIR results supported the interaction of the surfactants with the LDH. In addition, an increase in the thermal stability of the dodecanedioic acid intercalated HT was evidenced by the TGA method.