Nonionic Cosurfactants Research Articles

Synergisms between Surfactants, Polymers, and Alcohols to Improve the Foamability of Mixed Systems

In order to produce detergents with improved performance and good market acceptability, it is crucial to develop formulations with improved foamability and cleaning performance. The use of a delicate balance of surfactants and additives is an appealing strategy to obtain good results and enables a reduction in the amount of chemicals used in formulations. Mixtures of hydrophobically modified linear polymers and surfactants, as well as balanced mixtures with co-surfactants and/or hydrotropes, are the most effective parameters to control foamability and foam stability. In the present study, the effect of the addition of hydrophobically modified linear polymers, nonionic co-surfactants and hydrotropes, and their mixtures to anionic and zwitterionic surfactant aqueous solutions was evaluated. It was found that the presence of the hydrophobically modified polymer (HM-P) prevented the bubbles from bursting, resulting in better stability of the foam formed using zwitterionic surfactant solutions. Also, the surfactant packing was inferred to be relevant to obtaining foamability. Mixtures of surfactants, in the presence of a co-surfactant or hydrotrope led, tendentially, to an increase in the critical packing parameter (CPP), resulting in higher foam volumes and lower surface tension for most of the studied systems. Additionally, it was observed that the good cleaning efficiency of the developed surfactant formulations obtained a higher level of fat solubilization compared to a widely used brand of commercial dishwashing detergent.

Cosurfactants for controlling the surface properties of diluted solutions: Interplay with bulk rheology of concentrated solutions

The effect of the fatty alcohols (CnOH), fatty acids (CnAc), alkyltrimethyl ammonium bromides (CnTAB), alkyl sulfates (CnSO4Na) and alkyl acetates (CnAcet), with n varied between 6 and 12 C-atoms, on the surface properties of 0.5 wt% mixed solutions of sodium laurylether sulfate (SLES) and cocoamidopropyl betaine (CAPB) was studied. It was shown that the equilibrium surface tension decreases with increasing the cosurfactant chain-length. For example, the addition of C12OH to SLES+CAPB solution decreases its surface tension from 29 down to 22 mN/m. Both the dynamic surface tension and the characteristic adsorption time pass through a deep minimum when cationic or nonionic cosurfactants with 8 or 10 C-atoms are added. The minimum is particularly deep for nonionic surfactants with small head group (acids and alcohols) which destabilize the micelles and increase the rate of surfactant adsorption. The addition of anionic cosurfactants does not change the dynamic and equilibrium surface tensions of SLES+CAPB system. A strong correlation between the dynamic surface tension of diluted surfactant solutions (0.5 wt%) and the viscosity of the respective concentrated solutions (10 wt%) is established and explained for nonionic cosurfactants.

Rheology Control Using Nonionic Cosurfactants and pH Titration in an Amino Acid-Derived Surfactant Composition.

Sulfate-based formulations can be easily thickened by adding salt or amphoteric cosurfactants. However, sulfate-free and amino acid-based surfactants cannot. We explored an alternative thickening mechanism by studying the thickening effect of adding nonionic cosurfactants to a mixture of an amino acid-based surfactant, sodium lauroyl sarcosinate (SLSar), and a zwitterionic cosurfactant, cocamidopropyl hydroxysultaine (CAHS) at a 6:9 weight ratio. To characterize the formulations, we combined traditional rheometry with a state-of-the-art mesoscopic analysis of micelle dynamics obtained via diffusing wave spectroscopy. In addition, the formulations were characterized by cross-polarized light microscopy and dynamic light scattering. The cosurfactants studied included fatty alcohols, alkanediols, a fatty acid, and fatty alcohol ethoxylates (CnE3 and CnE6). Adding the nonionic cosurfactants increased the zero-shear viscosity up to 350 times the viscosity of the no-additive system at neutral pH. When pH titration was incorporated as a second thickening mechanism, the viscosity maximum was lower than the no-additive mixture. Furthermore, the pH of the viscosity maximum was shifted to higher pH for all systems except for CnE6, which shifted the maximum to lower pH. The nonionic amphiphiles also broadened the viscosity maximum, particularly in the C10OH system. Consequently, the C10OH system had a more favorable profile for development as a practical thickening system for an amino acid-based cleanser. Analysis according to the Zou and Larson micelle dynamics model revealed that the broadening effect was associated with substantially longer breakage times for the C10OH system (4-208 ms) compared to the no-additive system (4-38 ms).

Solubility of ionic surfactants below their Krafft point in mixed micellar solutions: Phase diagrams for methyl ester sulfonates and nonionic cosurfactants

HypothesisMany ionic surfactants with wide applications in personal-care and house-hold detergency show limited water solubility at lower temperatures (Krafft point). This drawback can be overcome by using mixed solutions, where the ionic surfactant is incorporated in mixed micelles with another surfactant, which is soluble at lower temperatures. ExperimentsThe solubility and electrolytic conductivity for a binary surfactant mixture of anionic methyl ester sulfonates (MES) with nonionic alkyl polyglucoside and alkyl polyoxyethylene ether at 5 °C during long-term storage were measured. Phase diagrams were established; a general theoretical model for their explanation was developed and checked experimentally. FindingsThe binary and ternary phase diagrams for studied surfactant mixtures include phase domains: mixed micelles; micelles + crystallites; crystallites, and molecular solution. The proposed general methodology, which utilizes the equations of molecular thermodynamics at minimum number of experimental measurements, is convenient for construction of such phase diagrams. The results could increase the range of applicability of MES–surfactants with relatively high Krafft temperature, but with various useful properties such as excellent biodegradability and skin compatibility; stability in hard water; good wetting and cleaning performance.

Evaluation of Ethoxylated Rapeseed Oil Fatty Acids Methyl Esters as Nonionic Co-Surfactants in Hand Dishwashing Liquids

Abstract The effect of ethoxylated rapeseed oil fatty acid methyl esters (ROFAME) on the viscosity, functional properties and skin compatibility of hand dishwashing liquids was analyzed. It was found that, over the test range, both the degree of ethoxylation and concentration in the formulation were essential for the properties of the evaluated products. Among others, this was due to the fact that ROFAME had the favorable effect of modifying the viscosity of these formulations to an acceptable range. The relationship between the concentration and degree of polyaddition of ROFAME on the detergent and foaming properties of the complete formulation was presented, showing their increase in comparison to the reference dishwashing liquid without ROFAME. With respect to the parameters relating to the skin irritant, the degree of skin dryness after dishwashing with the auxiliary surfactants was lower.

Control of surfactant solution rheology using medium-chain cosurfactants

The rheological properties of surfactant solutions play an important role in their applications. Here we study systematically how different cosurfactants affect the rheological properties of mixed solutions of the anionic surfactant sodium laurylether sulfate (SLES) and the zwitterionic cocoamidopropyl betaine (CAPB). Mixed SLES+CAPB solutions are used in various formulations due to their excellent foaming and cleaning properties. These solutions possess nearly Newtonian behavior and low viscosity. However, the addition of cosurfactants in low concentrations may significantly increase the viscosity of these solutions and even transform them into viscoelastic gels. Here we study systematically a wide range of ionic and nonionic cosurfactants with different head-groups, chain-lengths and structures of the hydrophobic tails (linear, branched, double bonded). We reveal an optimal chain-length of 8–10 carbon atoms of the cosurfactant molecules which ensures the highest viscoelasticity of the triple SLES+CAPB+cosurfactant solutions. Cationic cosurfactants and nonionic ones with small head-group (e.g. fatty alcohols and fatty acids) are most efficient in increasing the solution viscoelasticity. There is a hierarchy in the parameters of the cosurfactant molecules which govern this behavior − most important is the head-group charge, then the chain-length and, finally, the presence of branching and double bonds in the hydrophobic tails. The observed trends are explained with the effect of the cosurfactant molecules on the properties of the entangled wormlike micelles formed in these solutions.

Investigation of self-assembly properties and the effect of tween series co-surfactants on the stability of nonionic branched-chain glycolipid hexosomes

Sugar-based surfactants have recently drawn much attention due to their nonionic and bio-friendly properties. These glycolipids are also popular because they can be found in nature or synthesized (e.g. alkyl polyglucosides) from cheap natural resources. In this research, the liquid crystalline and self-assembly properties of a novel branch alkylated glycolipid, namely 2-hexyldecyl-β(/α)-d-glucoside (αβ-Glu-OC10C6), were studied using differential scanning calorimetry (DSC), optical polarizing microscopy (OPM) and small-angle X-ray scattering (SAXS). The αβ-Glu-OC10C6 in anhydrous condition formed a columnar phase with focal conic texture, whereas in the binary aqueous system, αβ-Glu-OC10C6 formed inverse hexagonal dispersions known as hexosomes. The critical aggregation concentrations (CACs) were studied for the branched-chain glycolipid when this was mixed with nonionic co-surfactants (Tween series). The addition of co-surfactants to the glycolipid dispersions reduced the CAC value of αβ-Glu-OC10C6, thus making the system more stable. The formation of mixed surfactant hexosomes was further investigated in terms of their particle size and morphology by using a particle sizer and a transmission electron microscope (TEM), respectively. Furthermore, the particle size variations and particle migration were investigated using light backscattering measurements for 24h. In the previous study, αβ-Glu-OC10C6 hexosomes produced were unstable because the balance between hydrophilic and lipophilic was not optimum to stabilize the formation of a stable double layer. Therefore, the addition of co-surfactant Tween series reduced the particle size and enhanced the stability of αβ-Glu-OC10C6. Thus, branched-chain glycolipid provided an alternative nonionic surfactant with interesting phase behaviour as a drug carrier system for various applications.

Fine-tuning the nonequilibrium behavior of oppositely charged macromolecule/surfactant mixtures via the addition of nonionic amphiphiles.

The various commercial applications of oppositely charged polyelectrolytes (P) and ionic surfactants (S) with added nonionic amphiphiles initiated intensive research on the polyion/mixed surfactant interaction. A large group of earlier studies revealed that one of the major effects of the nonionic cosurfactants is the suppression of the associative phase separation of P/S systems. In contrast, recent studies indicated that in the dilute surfactant concentration range the added uncharged amphiphile enhances the precipitation concentration range. In order to rationalize these observations, the mixtures of poly(diallyldimethylammonium chloride) (PDADMAC), sodium dodecyl sulfate (SDS), and dodecyl maltoside (C12G2) are investigated using a variety of experimental methods. It is shown that the nonionic cosurfactant has two distinct and competing impacts on the mixed surfactant binding onto the polyions. The composition dependent variation of the chemical potentials of the amphiphiles determines which of these effects is the dominant one, explaining the seemingly diverse earlier observations and their interpretations. We also demonstrate that the nonionic amphiphile affects considerably the nonequilibrium features of polyion/ionic surfactant complexation. Namely, the presence of the uncharged surfactant can destabilize the colloidal dispersion of P/S nanoparticles formed in the two-phase composition range. However, at the same concentration range highly stable dispersions of polyion/mixed surfactant nanoparticles can be produced through the application of a new two-step solution preparation technique. This method is based on the order of addition effect of the two surfactants which can be utilized in future scientific and industrial applications.

Positively Charged Microemulsions of Dexamethasone: Comparative Effects of Two Cosurfactants on Ocular Drug Delivery and Bioavailability

The objective of this investigation was to evaluate the potential of mucoadhesive chitosan-coated positively charged microemulsions (CH-MEs) of dexamethasone with respect to the change in nonionic cosurfactants. CH-MEs were prepared with different concentrations of surfactant and cosurfactant using the water titration method and coated with low-molecular-weight chitosan. All formulations displayed an average globule size between 85 and 187 nm and a positive surface charge. The optimized CH-MEs showed greater penetration of dexamethasone in the anterior segment of the eye, resulting in twofold and fourfold higher dexamethasone concentration than uncoated ME and drug suspension, respectively. The developed CH-MEs shows increases in ocular penetration and bioavailability.

Influence of non-ionic surfactant on electrostatic complexation of protein-coated oil droplets and ionic biopolymers (alginate and chitosan)

The purpose of this study was to examine the influence of a non-ionic cosurfactant (Tween 20) on the formation and properties of electrostatic complexes consisting of charged oil droplets and charged biopolymers. The mean droplet diameters in oil-in-water emulsions prepared using a membrane homogenizer were considerably larger when β-lactoglobulin (BLG) was used alone (≈8 μm), than when it was used in combination with Tween 20 (≈2 μm). The cationic oil droplets formed by membrane homogenization (4.0 μm pore size) were mixed with either alginate (anionic) solution (1% oil: 0–0.5% alginate: pH 3.5) or with alginate (anionic) and then chitosan (cationic) solutions (0.4% oil: 0.1% alginate; 0–0.2% chitosan: pH 4.5). The electrical characteristics, microstructure, and physical stability of the electrostatic complexes formed were determined. Under certain conditions multilayer emulsions consisting of oil droplets coated by alginate or alginate/chitosan layers were formed, whereas under other conditions microclusters consisting of aggregated oil droplets embedded within alginate or alginate/chitosan complexes were formed. The presence of the cosurfactant had a major impact on the electrical charge and dimensions of the electrostatic complexes formed. This study shows that various kinds of electrostatic complexes can be formed from charged oil droplets and charged biopolymers, and that their functional characteristics can be controlled using non-ionic cosurfactants.

Effect of Chain Length Compatibility between Surfactants and Co-Surfactants on Corrosion Inhibition of Steel

Corrosion inhibition effect of cationic surfactants, DTAB (Dodecyl Three methyl Ammonium Bromide) and TTAB (Tetradecyl Three methyl Ammonium Bromide) on low carbon steel was studied using weight loss, Open circuit potentional (OCP) and Electrochemical Impedance Spectroscopy (EIS) measurements. The effect of chain length compatibility on corrosion inhabitancy of surfactant and co-surfactant was investigated by C7OH (1-heptanol), C12OH (1-dodecanol) and C15OH (1-pentadecanol) as nonionic co-surfactants in acidic media at different concentrations of DTAB and TTAB. Data represented that the corrosion rate decreased by increasing concentration of DTAB and TTAB, independently. The effect of chain length compatibility on surfactant behavior was discussed. Decreasing of corrosion rate for DTAB+C12OH was more pronounced than other mixtures.

Electrochemical effect of Gemini Surfactant and Co-Surfactants on Corrosion Inhibition of Steel in Acid Medium

The effect of chain length compatibility on corrosion the inhibition effect of mixed inhibitor systems of cationic gemini surfactant, l,4-butan-bis (dodecyl dimethyl ammonium bromide) (designated as 12-4-12) with nonionic co-surfactants, C7OH (1-heptanol), C12OH (1-dodecanol) and C15OH (1-pentadecanol), on low carbon steel in acid medium was studied using weight loss, open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) measurements. The data demonstrated that the corrosion rate decreased by increasing surfactant concentration. In addition, less chain length difference causes more compatibility and inhibition on behavior of surfactant and co-surfactant mixture. Inhibition efficiency for C12OH + gemini surfactant was increased compared to the other mixtures explored.

The Chain Length Influence of Nonionic Co-Surfactants on Inhibition Effect of Cationic Surfactant on Steel Corrosion

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Effect of nonionic co-surfactants on corrosion inhibition effect of cationic gemini surfactant

The effect of chain length compatibility on corrosion inhibition effect of mixed inhibitor systems of cationic gemini surfactant (l,3-butan-bis(dodecyl dimethyl ammonium bromide) (designated as 12-4-12)), nonionic co-surfactants (C 7OH (1-heptanol), C 12OH (1-dodecanol) and C 15OH (1-pentadecanol)) on low carbon steel in acidic medium was studied using weight loss, open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) measurements. Data represented that the corrosion rate decreased by increasing surfactant concentration. In addition, less chain length difference causes more compatibility and inhibition efficiency on behavior of surfactant and co-surfactant mixture. Increasing of inhibition efficiency for C 12OH + gemini surfactant was more than other mixtures.

The chain length influence of cationic surfactant and role of nonionic co-surfactants on controlling the corrosion rate of steel in acidic media

The corrosion inhibition effect of cationic surfactants, DTAB (Dodecyl Trimethyl Ammonium Bromide) and TTAB (Tetradecyl Trimethyl Ammonium Bromide), on low carbon steel was studied using weight loss, open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) measurements. The effect of chain length compatibility on corrosion inhabitancy of surfactant and co-surfactant was investigated by C 7OH (1-heptanol), C 12OH (1-dodecanol) and C 15OH (1-pentadecanol) as nonionic co-surfactants in acidic media at different concentrations of DTAB and TTAB. Data represented that the corrosion rate decreased by increasing concentration of DTAB and TTAB, independently. The effect of chain length compatibility on surfactant behavior was discussed. Decreasing of corrosion rate for DTAB + C 12OH was more pronounced than other mixtures.

Interplay between the Surface Adsorption and Solution-Phase Behavior in Dialkyl Chain Cationic−Nonionic Surfactant Mixtures

Neutron reflectivity, NR, and surface tension have been used to study the adsorption at the air-solution interface of mixtures of the dialkyl chain cationic surfactant dihexadecyl dimethyl ammonium bromide (DHDAB) and the nonionic surfactants monododecyl triethylene glycol (C12E3), monododecyl hexaethylene glycol (C12E6), and monododecyl dodecaethylene glycol (C12E12). The adsorption behavior of the surfactant mixtures with solution composition shows a marked departure from ideal mixing that is not consistent with current theories of nonideal mixing. For all three binary surfactant mixtures there is a critical composition below which the surface is totally dominated by the cationic surfactant. The onset of nonionic surfactant adsorption (expressed as a mole fraction of the nonionic surfactant) increases in composition as the ethylene oxide chain length of the nonionic cosurfactant increases from E3 to E12. Furthermore, the variation in the adsorption is strongly correlated with the variation in the phase behavior of the solution that is in equilibrium with the surface. The adsorbed amounts of DHDAB and the nonionic cosurfactants have been used to estimate the monomer concentration that is in equilibrium with the surface and are shown to be in reasonable qualitative agreement with the variation in the mixed critical aggregation concentration (cac).

Wormlike micelles and microemulsions in aqueous mixtures of sucrose esters and nonionic cosurfactants

A study of the phase and rheological behavior of sucrose hexadecanoate (C16SE)/cosurfactant/water systems in the presence of solubilized oil, using complementary techniques such as dynamic light scattering and small angle X-ray scattering, is presented. Viscoelastic wormlike micellar solutions are found when a nonionic lipophilic cosurfactant is added to C16SE aqueous systems. Contrary to previous reports, the effect of oil solubilization on these wormlike micelles is not unique and depends on several factors. Linear alkyl chain oils that tend to solubilize in the micellar core have a disrupting effect, decreasing the relaxation time and the viscosity of the systems. This effect is larger as the molecular volume of oil increases and as the solubility of the cosurfactant in oil increases. On the other hand, oils that penetrate in the palisade layer, such as p-xylene, induce micellar growth and have a thickening effect at a given micellar composition. Thermodynamic considerations are used to explain the experimental results.

Nonionic Cosurfactants in AOT Reversed Micelles: Effect on Percolation, Size, and Solubilization Site

The effect of nonionic cosurfactants on AOT reversed micellar interface and micelle/micelle interactions was studied. The change on the percolating temperature induced by these cosurfactants was determined for several water contents, micelle concentration, and cosurfactant type and concentration. Two types of cosurfactants were used, linear chained alkyl alcohols and poly(oxyethylene) alkyl ethers (CiEj). If an alcohol was added to the microemulsion, a shift in percolation to higher temperature was observed. The opposite was observed for the CiEj. The apparent hydrodynamic radius for the same systems was determined using dynamic light scattering. The apparent hydrodynamic radius of the alcohol-containing microemulsions was only slightly dependent on the concentration and chain size of the alcohol. The CiEj had the opposite effect, the apparent hydrodynamic radius increased for bigger head group sizes and higher concentrations. These results were interpreted in terms of a decrease or an increase of the fluidity of the interface layer. A solubilization site for the cosurfactants is proposed based on this interpretation of the results. Using the experimental results and an association model, the clustering enthalpy and entropy were determined. The clustering process was found to be endothermic and entropically driven.

The stability of bicontinuous microemulsions: A molecular theory of the bending elastic properties of monolayers comprised of ionic surfactants and nonionic cosurfactants

In recent work, a statistical thermodynamic approach was used [J. Chem. Phys. 99, 7124 (1993)] to study curvature elastic properties of self-assembled films of nonionic surfactants at the oil/water interface in microemulsions. In the present work, this approach is extended to investigate films comprised of mixtures of ionic surfactants and nonionic cosurfactants, commonly used to form droplet and bicontinuous microemulsions. A simple description of the interactions among charged head groups is incorporated into the existing theoretical framework, yielding predictions of spontaneous curvature, mean and Gaussian elastic moduli, molecular area, and chain segment distributions as a function of monolayer composition, the strength of the electrostatic repulsion, and the lengths of the surfactant and cosurfactant chains. These predictions are found to be in good agreement with measured curvature elastic and structural properties, and with characteristic features of the phase diagrams of well-studied systems, particularly with respect to the effect of concentration of added electrolyte and the chain length and concentration of the alcohol (cosurfactant). More importantly, the results provide an unexpected explanation of the role of the alcohol in the stabilization of bicontinuous microemulsions, i.e., to form a monolayer of zero spontaneous curvature and low bending elastic moduli.

Production of oil-containing polyterephthalamide microcapsules by interfacial polymerization. An experimental investigation of the effect of process variables on the microcapsule size distribution.

Oil-containing polyterephthalamide microcapsules were prepared by the interfacial polymerization technique. The inner phase of the microcapsules consisted of a mixture of an organic solvent, toluene, and a commercial oil, santosol. Microcapsules with mean Sauter diameters in the range 0.5-20 microns were prepared by varying the rate of agitation (2000-7000 rpm) and the concentration of a poly(vinyl alcohol) stabilizer (0.1-1.0 wt% w/v), in the presence of several ionic and non-ionic cosurfactants. High agitation rates resulted in a significant reduction of the mean size of the oil droplets, although a slight increase in the breadth of the droplet size distribution was observed. High concentrations of PVA also resulted in a decrease of the microcapsule size, although the effect of stabilizer concentration was generally less important than that of the agitation speed. Finally, the effect of various ionic and non-ionic cosurfactants on the microcapsule size distribution was investigated. It was found that the addition of a cosurfactant significantly reduced the mean droplet size of the initial emulsion, leading to the formation of microcapsules in the submicron range.