Polyoxyethylene Alkyl Ether Research Articles

A Coarse-Grained MARTINI Model of Polyethylene Glycol and of Polyoxyethylene Alkyl Ether Surfactants

Nonionic surfactants are used for the isolation and purification of membrane proteins, as well as for the study of fundamental aspects of protein diffusion in membranes. Here we present a new coarse-grained model of polyethylene glycol (PEG) and of the family of polyoxyethylene alkyl ether (C(i)E(j)) surfactants. The model is compatible with the MARTINI coarse-grained force-field for lipids and proteins. We validate the model by comparing molecular dynamics simulations with experimental data. In particular, we show that the model reproduces the phase behavior of water-surfactant mixtures as a function of water concentration. We also simulate the self-assembly of two ternary mixtures that have been used for the experimental measure of protein diffusion coefficients. The first includes a cosurfactant that affects the curvature of the surfactant bilayers; the second is a mixture of C(i)E(j) surfactants, alkanes and water. In both cases, the results of self-assembly simulations are in agreement with experimental observations and pave the way to the use of the surfactant model in combination with MARTINI peptides and proteins.

Rotational dynamics of coumarin 153 in non-ionic mixed micelles of n-octyl-β-d-thioglucoside and Triton X-100

Rotational diffusion of the neutral probe coumarin 153 has been examined in a mixed surfactant system containing n-octyl-β-D-thioglucoside (OTG) and Triton X-100 (TX100), two non-ionic surfactants belonging to the alkyl glucoside and polyoxyethylene alkyl ether families, respectively. Both steady-state and time-resolved fluorescence measurements indicate that the polarity of the dye decreases slightly as the amount of ethoxylated surfactant in the mixed micelle increases. This behaviour can be attributed to migration of the probe towards the inner region of the micellar palisade layer as a result of the increasing hydration induced by the presence of TX100. The anisotropy decay curves, r(t), were well fitted to a biexponential function, characterized by two reorientational times of the probe in the micellar pseudophase. The experimental data were analyzed on the basis of the two-step and wobbling-in-a-cone model, and the results obtained correlated with the changes that occur in the palisade layer of the mixed micelles due to the different structure and nature of the head groups of both surfactants. It was found that, although the average reorientation time of the probe molecule is almost unaffected with the participation of the ethoxylated surfactant, the observed increase in the generalized order parameter suggests a certain rise in the compactness of the mixed micelles.

Photo-Fenton degradation of non-ionic surfactant and its mixture with cationic or anionic surfactant

The oxidative degradation of non-ionic surfactants by the photo-Fenton process has been examined. The photo-Fenton degradation kinetics of mixtures of non-ionic surfactant and other type surfactants has been also investigated since mixtures of non-ionic and ionic surfactants are commonly used to utilize their synergistic effects in many practices. Effects of operating parameters such as dosages of Fenton reagents (iron and hydrogen peroxide) and UV light intensity on the degradation of commercial non-ionic surfactant Sannonic SS-90 (polyoxyethylene alkyl ether) were studied. Although the dosages of the Fenton reagents increased the degradation rate up to the optimum dosages, further addition of the reagents could not enhance the degradation rate. Excess dosages of Fe and H2O2 caused excess OH radicals which could be a scavenger of OH radicals and as a result could not enhance the degradation of the surfactant. The increase in UV light intensity resulting in the faster photo-Fenton process or the enhancement of OH radical formation rate led to the increase in degradation rate of non-ionic surfactant. Although the existence of the anionic surfactant (sodium dodecylbenzene sulphonate) would inhibit the degradation of the non-ionic surfactant due to the formation of complex with Fe ion, the existence of cationic surfactant (dodecyltrimethyl ammonium chloride) affected insignificantly the photo-Fenton degradation process of the non-ionic surfactant.

Study on Drilling Fluid Technology of Eliminating Bit Balling by Changing Wettability

Using triethanolamine, vegetable fatty acid, alkyl polyoxyethylene alkyl ether sulfuric acid ester and dimethyl sulfate as raw materials, a new kind of anti-balling additive for drilling engineering (WORB) was synthesized. The wetting property and anti-balling performance of WORB were investigated according to the experiments of wettability, surface tension and absorption effect. The results indicate that the adsorption of WORB on the surface of the cuttings is monolayer adsorption, which can avoid repeated cutting caused by the agglomeration of cuttings. WORB can alter the wettability of rock surface and the inner pores of the rock to reduce the surface tension of the rocks. Moreover, WORB can form multilayer chemical and physical adsorption on the surface of drill bits and BHA in the form of oriented adsorption of organic phosphine.

Micellar size and phase behavior in n-octyl-β-d-thioglucoside/Triton X-100 mixtures: The effect of NaCl addition

The temperature and NaCl concentration dependence of the size of mixed micelles of n-octyl-β-d-thioglucoside (OTG) and Triton X-100 (TX100), two non-ionic surfactants belonging to the alkyl glucosides and polyoxyethylene alkyl ether families, respectively, has been investigated using the dynamic light scattering technique. Micellar size increases with temperature, with this micellar growth occurring faster when the temperature approaches the cloud point temperature. The extent of this growth is less pronounced at higher relative proportions of OTG in solution. In addition, the cloud point temperature was investigated for aqueous and NaCl solutions of OTG and Triton X-100 mixtures. The experimental results can be explained assuming the clouding process to be a liquid–liquid phase separation which takes place as a result of reduced hydration of the head group in the surfactant molecules caused by the temperature rise. The thermodynamic parameters of the clouding phenomenon have been calculated using the phase-separation model and considering the cloud point to be the threshold temperature for solubility. This study found that the enthalpy–entropy compensation relationship holds for this process.

Wetting dynamics of polyoxyethylene alkyl ethers and trisiloxanes in respect of polyoxyethylene chains and properties of substrates

Wetting performance of aqueous solutions of trisiloxane surfactants (TEOn) and polyoxyethylene alkyl ethers (C10EOn) on polypropylene, Parafilm and Teflon AF surfaces in a wide range of concentrations has been investigated. Surfactants C10EOn only facilitate partial wetting of water on all surfaces, but TEOn surfactants induce superspreading on polypropylene and Parafilm at room temperature (22°C) at critical wetting concentration (CWC). Influence of the length of EO chains on wetting ability has a completely different character for C10EOn and TEOn surfactants. In the case of C10EOn the final contact angle increases on all substrates used with increasing number of EO units. However, the final contact angles for droplets of TEOn solutions decrease with increasing of n(EO) reaching a minimum values at n(EO)=6 at the critical aggregation concentration (CAC), or show complete spreading (the final contact angle is nearly zero) for n(EO)=5–8 at 1 CWC on moderately hydrophobic substrates. Temperature-dependent spreading behaviour of both TEOn and C10EOn surfactant solutions has also been studied. It has been shown for the first time, that tuning of spreading performance with temperature for polyoxyethylene alkyl ether surfactants is possible. The increase of spreading capability for both trisiloxane surfactant solutions and polyoxyethylene alkyl ethers solutions is observed at temperature close to the cloud point for a given surfactant.

Synthesis and Surface Activity of Guerbet Betaine Surfactants with Ethylene Oxide Groups

Abstract Three series of Guerbet betaine surfactants with ethylene oxide groups were synthesized by Guerbet alkyl polyoxyethylene ether surfactants, epichlorohydrin, dimethylamine and sodium chloro-acetate. Their structures were confirmed by MS. The critical micelle concentrations (CMC) and surface tension at CMC (γCMC) of all prepared Guerbet betaine surfactants were determined by K100C processor tensiometer with the Wilhelmy-plate method at 25°C. It is found that synthesized surfactants exhibit great efficiency of reducing surface tension. As the number of ethylene oxide groups increases, the γCMC gradually increases. As the length of the hydrophobic chain of Guerbet betaine surfactants increases, the γCMC increases firstly and then decreases.

Self-organization of surfactant molecules on immersed gold substrates

The adsorption of surfactants on solid substrates is subject of both fundamental and applied interests. Many nano-sized systems used in drug delivery formulations in pharmacological sciences are constituted by surfactants alkyl ether sulfates, CnSO4, and polyoxyethylene alkyl ethers, CnEm. The aim of this work was to study the interaction of dilute solutions (below the critical micelle concentration, CMC) of different ionic (the alkyl ether sulfates C10SO4, C12SO4, C14SO4 and C18SO4) and nonionic surfactants (the alkyl ethers C10E8, C12E8, C14E8, C16E8 and C18E8) with the surface of a polycrystalline gold electrode of a electrochemical quartz crystal microbalance (EQCM). The gold electrode surfaces, after the film adsorption, were characterized with the Atomic Force Microscope (AFM) and potentiostatic measurements.

Preparation and Surface Activities of Modified Double‐Tailed Anionic Surfactants

AbstractWe prepared a series of modified double‐tailed surfactants containing two identical nonionic moieties and an anionic spacer group. Each surfactant was prepared through the reaction of two moles of polyoxyethylene alkyl ether with one mole of maleic anhydride to form a diester having a gemini structure; an anionic sulfonate group was then introduced through reaction of the olefinic bond with sodium hydrogen sulfite. The structures of these compounds were confirmed through infrared spectroscopy, nuclear magnetic resonance spectroscopy, and elemental analysis. These modified double‐tailed surfactants exhibit good surface properties, including low‐foaming, wetting and lime‐soap dispersing power. Their excellent dispersing abilities toward disperse dyes were due to the double‐tailed structures of the surfactants, with the hydrophobic moieties increasing the binding ability to the dyes and its anionic units providing dispersing power.

Aqueous mixtures of di-n-decyldimethylammonium chloride/polyoxyethylene alkyl ether: Dramatic influence of tail/tail and head/head interactions on co-micellization and biocidal activity

Mixed aggregate formation and synergistic interactions of binary surfactant mixtures of di-n-decyldimethylammonium chloride, [DiC10][Cl], with polyoxyethylene alkyl ethers, CiEj (i=10, 12, j=4, 6, 8), have been investigated for various [DiC10][Cl]/CiEj ratios. The critical aggregation concentration of the binary mixtures has been determined by tensiometry, and the aggregate characteristics (i.e., size and composition, free ammonium concentration) have been estimated using the pulsed field gradient NMR spectroscopy and a [DiC10]-selective electrode. Diffusion coefficient measurements of micelles confirmed the synergistic interaction between the surfactants. It is thus shown that the formation of surface monolayers and mixed aggregates from [DiC10][Cl]/C10Ej mixtures is driven by both tail/tail and head/head interactions, whereas [DiC10][Cl]/C12Ej co-aggregation is mainly driven by tail/tail interactions. As a consequence, the co-aggregation phenomenon notably influences the biocidal activity of [DiC10][Cl] on the Candida albicans fungi. In the presence of C12Ej, the biocidal activity of the ammonium salt is inhibited due to the trapping of the cationic surfactants in the mixed aggregates, whereas in the presence of C10Ej, the biocidal activity of the surfactant mixture is maintained. The mode of action is also confirmed by a faster increase in the zeta potential of a C. albicans suspension in the presence of [DiC10][Cl]/C10E8 than in the presence of [DiC10][Cl]/C12E8. Therefore, a judicious adjustment of the alkyl (i) and polyoxyethylene (j) chain lengths of CiEj avoids its antagonistic effect on the biocidal activity of [DiC10][Cl].

Micellization and Phase Behavior of Binary Mixtures of Anionic and Nonionic Surfactants in Aqueous Media

The micellization and phase behavior of the binary mixed systems comprising the anionic surfactants sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/sodium alkyl phenol ether sulfate (APES) and nonionic polyoxyethylene alkyl ether surfactants (C10E8/C10E10/C13E10) have been investigated by surface tension, fluorescence spectroscopy, and cloud point measurements. Various micellar characteristics, surface active properties, thermodynamic parameters, aggregation numbers, and Stern–Volmer constants have been evaluated for these systems. Lower cmc values, negative interaction and thermodynamic parameters, higher aggregation numbers, and improved surface active properties for the proposed mixed systems indicate the existence of strong synergistic interactions and the formation of thermodynamically stable mixed micelles. Observed elevation in the cloud point (CP) shift suggests the formation of charged micelles that increases the intermicellar repulsions and poses a hindrance to the coacervation of micelles. It sub...

Collapse and coacervation of a lamellar phase by inter-headgroup bridging

We report the collapse of an electrostatically swollen surfactant lamellar phase above a critical concentration of an added nonionic surfactant due to hydrogen bonding between the two types of headgroups. At still higher concentrations of the neutral surfactant a temperature-driven lamellar to coacervate transition is observed. Small-angle X-ray diffraction pattern of the coacervate can be modeled as arising from bilayers with short-range positional correlations, whereas cryo-scanning electron microscopy images show bilayer-like features riddled with pores. Very similar behavior is found when the nonionic polyoxyethylene alkyl ether surfactant is replaced by polyethylene glycol of sufficiently high molecular weight.

Structure–Behavior–Property Relationship Study of Surfactants as Foam Stabilizers Explored by Experimental and Molecular Simulation Approaches

A multiscale stability study of foams stabilized by sodium dodecyl sulfate (SDS), sodium dodecylbenzene sulfonate (SDBS), and sodium polyoxyethylene alkylether sulfate (AES) was conducted, to investigate the relationship of surfactant molecular behavior and interfacial monolayer configuration of foam film to the foam film properties. Molecular dynamic (MD) simulations using a full-atom model was utilized to explore the microscopic features of the air/liquid interface layer. Several parameters such as the distribution of surfactant head groups and the order degree of surfactant hydrophobic tails were used to describe the molecular adsorption behavior. The effect of molecular structure on the nature of the foam film and the impact on the dynamic stability of wet foam is discussed. In the experimental evaluation, the SDBS foam films manifest strong stiffness and low viscoelasticity as shown by the interfacial shear rheology determination as well as texture analyzer (TA) measurement results, which agree very well with the array behavior of SDBS molecules at the air/water interface as described by the simulation results and is identified to be the reason for the poor dynamic stability. Comparing the molecular structure of SDS, SDBS, and AES, the special contributions of the linking groups such as the O atom, the phenyl group, and the EO (oxyethyl) chain to the interfacial array behavior of surfactants were characterized. It is concluded that microhardness of the foam film enhanced by rigid linking groups favors static foam stability but decreases the dynamic foam stability, while viscoelasticity of the foam film enhanced by soft linking groups increases the dynamic foam stability.

Influence of formulation variables in transdermal drug delivery system containing zolmitriptan

The effects of different formulation variables including pressure sensitive adhesive (PSA), thickness of the matrix, solvent system, inclusion of crystallization inhibitor, loading amount of drug and enhancers on the transdermal absorption of zolmitriptan were investigated. Acrylic adhesive with hydroxyl functional group provided good adhesion force and high flux of zolmitriptan. Pseudopolymorphs of zolmitriptan were found to possess different solid-state properties that affected the permeation rate. Polyoxyethylene alkyl ethers significantly increased the permeation of zolmitriptan through hairless mouse skin. However, these enhancers induced crystallization of zolmitriptan. Kollidon ® 30 delayed the crystallization without altering the permeation profile of zolmitriptan. Stability studies suggested that terpenes did not induce crystallization of zolmitriptan in the patch and stable formulations could be produced by using cineole and limonene, or their combination.

Characterization of mixed non-ionic surfactants n-octyl-β-d-thioglucoside and octaethylene–glycol monododecyl ether: Micellization and microstructure

Mixed micelles of n-octyl-β-d-thioglucoside (OTG) and octaethylene–glycol monododecyl ether (C12E8), two non-ionic surfactants belonging to the alkyl glucosides and polyoxyethylene alkyl ether families, respectively, were investigated by using light scattering and fluorescence probe techniques. From the determination of the critical micelle concentration (cmc), by the well-established pyrene 1:3 ratio method, it was found that the mixed system behaves ideally, the micellization process being clearly controlled by the ethoxylated surfactant. The micellar hydrodynamic radius as a function of temperature, composition and concentration was obtained by dynamic light scattering measurements. It was observed that the micellar size increases with temperature, this growth being more pronounced as the relative proportion of the ethoxylated surfactant was increased. The behavior of the micellar size with the total surfactant concentration was also found to be dependent on temperature and composition. The clouding temperature, characteristic of the ethoxylated surfactants, was increased with the addition of the sugar surfactant. Lastly, possible structural changes in the micellar palisade layer were examined by steady-state fluorescence anisotropy in conjunction with time-resolved fluorescence studies with the hydrophobic probe coumarin 6 (C6). The obtained results indicate that the participation of the ethoxylated surfactant induces a slightly more polar palisade layer, whereas the probe carries out a faster rotational reorientation as a result of a less compact environment. All these observations were attributed to the different structure of the head groups of both surfactants and, as a consequence, to their different hydration.

Demonstration of maximum solubilization in a polyoxyethylene alkyl ether series of non-ionic surfactants.

The solubilization of azobenzene, menaphthone, cortisone acetate, and griseofulvin was measured in a series of non-ionic surfactants of structure CH3[CH2](m-1) [OCH2CH2]1.25m OH, where m varied from 8 to 18. Maximum solubilization occurs when m = 16 (the hexadecyl alkyl ether). This is explained in terms of changes in the oxyethylene mantle close to the micelle core/mantle interface, which appears to be the main locus of solubilization. Micellar properties of CH3[CH2]17[OCH2CH2]22OH are also reported and discussed.

Safety aspects of non-ionic surfactant vesicles: a toxicity study related to the physicochemical characteristics of non-ionic surfactants.

Two different toxicity models were used to assess the relationship between the physicochemical properties of non-ionic surfactant vesicles (NSVs), and the safety of these vesicles for topical drug administration. The vesicles used in this study consisted of polyoxyethylene alkyl ethers (CnEOm) in which the number of C atoms (n) varied between 12 and 18 and the number of oxyethylene units (m) between 3 and 7. The physicochemical properties of the vesicles are described in terms of hydrophilic-lipophilic balance (HLB) values, and critical micelle concentrations (CMC), and the rigidity of the bilayers as determined by the gel-liquid transition temperatures and the cholesterol content of the bilayers. The first toxicity model, comprising the measurement of the ciliary beat frequency, is a tool to assess the safety of intranasally applied formulations. Studies using this ciliotoxicity model revealed that by increasing the length of the alkyl chain of the surfactant, a decrease in toxicity was observed. The opposite correlation was found if the length of the polyoxyethylene headgroup was increased. Furthermore, it was observed that gel-state vesicles produce less of an effect on the ciliary beat frequency than liquid state vesicles. The second toxicity model, comprising the determination of cell proliferation of human keratinocytes, is a method to assess skin irritancy. In contrast to the ciliotoxicity model the length of the polyoxyethylene headgroup and of the alkyl chains did not seem to have an effect on the safety of the vesicles.(ABSTRACT TRUNCATED AT 250 WORDS)

A Surface Rheological Study of Polyoxyethylene Alkyl Ether Carboxylic Salts and the Stability of Corresponding Foam

The dynamic dilational viscoelastic properties of polyoxyethylene alkyl ether carboxylic salts at the air-water interface were investigated by drop shape analysis method and their foam stability were measured by Bikerman Method. The influences of time, dilational frequency, and bulk concentration on surface dilational modulus and phase angle were expounded. The results show that the surfactant with the longest straight-chain shows the highest dilational modulus, which in agreement with the best foam stability. However, the foam stability of branched-alkyl chain surfactant cannot be explained in terms of film elasticity alone.

Inhibitory effect of drug-free hybrid liposomes on metastasis of human neuroblastoma

Hybrid liposomes composed of vesicular and micellar molecules have been used as drug-delivery systems. It has become clear that hybrid liposomes alone have an inhibitory effect against the growth of various tumor cells. The present study was designed to determine whether a drug-free hybrid liposome composed of dimyristoylphosphatidylcholine (DMPC) and polyoxyethylenealkyl ether (EO) [90 mol% DMPC/10% C(12)(EO)(21) (HL21), 90 mol% DMPC/10% C(12)(EO)(23) (HL23), or 90 mol% DMPC/10% C(12)(EO)(25) (HL25)], inhibit the liver metastasis of human neuroblastoma cells and thus increases survival. A human neuroblastoma cell, TNB9, and BALB/C-nu/nu athymic mice were used in this study. First, we determined the inhibitory effect of the hybrid liposomes on TNB9 cells in vitro. Next, to determine the inhibitory effect of the hybrid liposomes on metastasis of neuroblastoma cells to the liver, we made a murine hepatic metastasis model by implanting TNB9 cells (2 × 106) in the spleen of the mice and compared anatomic appearance, weights, and histological findings of the livers of treated mice and control mice 60 days after the beginning of a 7-day intraperitoneal injection of a hybrid liposome. We also compared survival rates using the Kaplan-Meier method. In mice implanted with TNB9 neuroblastoma cells and treated with HL21 or HL25, no histological evidence of metastasis was found, the weight of the liver was normal, and survival was a mean of 88 and 87.9 days, respectively. In contrast, mice treated with HL23 and control mice had countless tumor cell masses histologically, their liver weight was increased, and their survival was 73.0 and 68.6 days, respectively. Two kinds of hybrid liposomes, HL21 and HL25, inhibit metastasis of human neuroblastoma cells to the liver, and thus increase survival.

Polyoxyethylene alkyl and nonyl phenol ethers complexation with potato starch

Starchy soil removal efficiency when cleaning food industry equipment can be affected by surfactant–starch complexes. Polyoxyethylene alkyl and nonyl phenol ethers complexation with potato starch has been studied by surface tension measurements. All surfactants assayed yield inclusion complexes with starch after a critical concentration of association was achieved. No starch saturation was observed throughout complexation until micellization, with bound surfactant being proportional to the total added surfactant. This bound/total surfactant ratio and the critical concentration of association seemed to depend mainly on the surfactant alkyl chain length. Unlike fatty alcohol ethoxylates, the nonyl phenol ethoxylate was feebly bound likely caused by its aromatic moiety. Binding isotherms and Scatchard plots suggested surfactants positive cooperative and non-cooperative binding with amylose and amylopectin respectively. Phosphate buffer raised surfactants binding capacity, ascribed either to an increase in cooperativity or to a reduction in the number of glucose units required to bind a surfactant molecule.