Physicochemical properties of alcohol polyoxyethylene ether acetate/alkyl ethoxy polyglycoside surfactant mixtures

Alcohol polyoxyethylene ether acetates (AECs) containing 10 ethylene oxide (EO) groups and a fatty chain of C_16-18 mixed with alkyl ethoxy polyglycoside can incorporate the excellent properties compared to the individual surfactants, which can broaden the range of applications in daily chemical industry. The physicochemical properties of the mixed surfactant systems were investigated by surface tension, wetting, foaming, and emulsification measurements. The phase behavior of the mixed systems was also studied. Synergism was obtained in surface tension, wetting, and foaming ability.     

脂肪醇聚氧乙烯醚磺酸钠的性能研究

对合成的不同碳链脂肪醇聚氧乙烯醚磺酸钠(AnESO,EO=3,n=14,16,18)的应用性能及与重烷基苯磺酸钠(HABS)的复配进行了研究.结果表明:(1)AnESO的γcmc分别为36.16 mN·m-1,35.47 mN·m-1和34.85 mN·m-1,A14ESO发泡性较好,A18ESO稳泡性较强,耐钙稳定性分别达到了8700mg/L,9500mg/L和10000mg/L,耐盐性为A18ESO ＞ A16ESO ＞A14ESO;(2)AnESO与HABS复配可以改善HABS的耐盐性,AnESO/HABS体系与大庆原油间的界面张力在ω(AnESO):ω(HABS)约为3:7时最低,达到了3.9×10-2mN·m-1,1.4×10-2mN·m-1和4.3×10-3mN·m-1,A18ESO/HABS体系油水界面张力在NaCl含量为0～15000mg·L-1下均达到10-3mN·m-1数量级.     

Physicochemical properties of mixed surfacant systems: sodium dodecyl benzene sulfonate with triton X 100

The physicochemical properties of a mixed surfactant system were studied under various conditions. The surfactants were anionic sodium dodecyl benzene sulfonate and nonionic Triton X 100. Variation of specific conductivity with concentration was used to determine the critical micelle concentration of anionic as well as the mixed surfactants. Iodine solubilization method was used to determine the CMC of the nonionic surfactant. The interaction parameter between the surfactant molecules were calculated. The wetting, foaming and detergent properties of mixed surfactant systems were studied. The variation of contact angle of the solution with teflon surface as a function of surfactant concentration was found to be a reasonably good method to determine the critical micelle concentration. Viscosity and cloud points were also determined. All these quantities are discussed. Received: 14 January 1998 Accepted: 11 June 1998     

A review on experimental studies of surfactant adsorption at the hydrophilic solid-water interface

The progresses of understanding of the surfactant adsorption at the hydrophilic solid-liquid interface from extensive experimental studies are reviewed here. In this respect the kinetic and equilibrium studies involves anionic, cationic, non-ionic and mixed surfactants at the solid surface from the solution. Kinetics and equilibrium adsorption of surfactants at the solid-liquid interface depend on the nature of surfactants and the nature of the solid surface. Studies have been reported on adsorption kinetics at the solid-liquid interface primarily on the adsorption of non-ionic surfactant on silica and limited studies on cationic surfactant on silica and anionic surfactant on cotton and cellulose. The typical isotherm of surfactants in general, can be subdivided into four regions. Four-regime isotherm was mainly observed for adsorption of ionic surfactant on oppositely charged solid surface and adsorption of non-ionic surfactant on silica surface. Region IV of the adsorption isotherm is commonly a plateau region above the CMC, it may also show a maximum above the CMC. Isotherms of four different regions are discussed in detail. Influences of different parameters such as molecular structure, temperature, salt concentration that are very important in surfactant adsorption are reviewed here. Atomic force microscopy study of different surfactants show the self-assembly and mechanism of adsorption at the solid-liquid interface. Adsorption behaviour and mechanism of different mixed surfactant systems such as anionic-cationic, anionic-non-ionic and cationic-non-ionic are reviewed. Mixture of surface-active materials can show synergistic interactions, which can be manifested as enhanced surface activity, spreading, foaming, detergency and many other phenomena.     

Study on the properties of a polyvinylacetate film at the air-water interface

Isotherms of surface pressure against surface area for a polyvinylacetate (PVAc) film at the air-water interface were determined at 20.52°C. Measurements of surface moment, hysteresis, and pressure relaxation in a constant area were subsequently conducted at appropriate area regions for elucidation of the correlation of properties and conformations of PVAc film. It is concluded that the film is stable and exhibits a perfectly reversible compression in the areas larger than 13 Ų/repeat-unit but assumes three different conformations for three regions (70-42), (42-25), and (25-13) Ų/repeat-unit, respectively. Finally, a twisting chain loop model is proposed for the interpretation of hysteresis and pressure relaxation occurring in the areas near and in the collapse region.     

Complex of lysozyme and Myramistin: formation and adsorption at the water–xylene interface

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Effect of SDBS on interfacial electron transfer at the liquid/liquid interface by thin layer method

The effect of an adsorbed anionic surfactant sodium dodecyl benzene sulfonate(SDBS) on electron transfer(ET) reaction between ferricyanide aqueous solution and decamethylferrocene(DMFc) located on the adjacent organic phase was investigated for the first time by thin layer method.The adsorption of SDBS at the interface resulted in a decay in the cathodic plateau current of bimolecular reaction with increasing concentrations of SDBS in aqueous phase.However,the rate constant of electron transfer(k_(et)) i...     

Influence of maltodextrins with different dextrose equivalent on the thermodynamic properties of legumin in a bulk and at the air–water interface

This paper presents the influence of the potato maltodextrins with different dextrose equivalent (DE 2, 6 and 10) on the legumin thermodynamic properties in the bulk aqueous medium and at the air–water interface both in the simple mixed solutions and under the covalent complex (conjugate) formation (by the Maillard reaction), at pH 7.0 and ionic strength of 0.05 mol dm⁻³. The weak net attractive interaction between legumin and maltodextrin has been found in an aqueous medium by both the light scattering and the mixing calorimetry methods. On the basis of both the mixing and differential scanning calorimetry data a hydrogen bonding is supposed to be fundamental for this interaction. It was found that these attractive interactions produced an increase in the protein hydrophilicity and consequently a decrease in the protein surface activity. The effect was more pronounced for the maltodextrin with the largest dextrose equivalent (DE 10). The covalent complexation between legumin and maltodextrin induced the change of the fine hydrophobic–hydrophilic balance in the protein globule due to both addition of the hydrophilicity of the covalently attached polysaccharide and the partial protein unfolding as a result of the such kind of attachment. The combined data of tensiometry, light scattering, mixing and differential scanning calorimetry demonstrated the importance of the maltodextrin polymerization (DE) in controlling both the protein hydrophilicity (thermodynamic affinity for the aqueous phase) and surface activity.     

Solid state photoreactions occurring at the interface between crystallites of two different organic compounds

This paper deals with the solid state bimolecular photoreactions occurring at the interface between crystallites of two different organic compounds prepared as a polycrystalline mixture by melting-resolidification. The photoreactions include the photoaddition of NH compounds to aromatic and olefinic double bonds, hydrogen abstraction, condensation reaction via photoelectron transfer and [2+2] photoaddition. Particular attention is focused on the characterization of the polycrystalline mixture, the selectivity of the photoreactions in the solid state compared with those in the solution phase and the factors controlling the photoreactions.     

Interfacial characteristics of food emulsifiers (proteins and lipids) at the air-water interface

Factors affecting the interfacial characteristics (structure, stability, interfacial rheology, molecular diffusion, and rate of film formation) of food emulsifiers (polar lipids and proteins) at the air-aqueous phase interface are reviewed. The effect of interfacial and aqueous phase (water, and aqueous solutions of ethanol, glycerol, sugars, electrolytes, and pH) compositions have been analyzed as variables. Many measurement methods—such as tensiometry (Wilhelmy plate and pendant drop methods), and Langmuir- and Wilhelmy-type film balances—have been used in the experiments. The effect of the interfacial, aqueous phase composition, and operational conditions (surface density, surface pressure, and temperature) of food emulsifiers (lipids and proteins) at the air-aqueous phase interface are discussed.     

Synthesis and monolayer film of a series of new twin-tailed gemini cationic surfactants at the air/water interface

A series of new dimeric surfactants, twin-tailed gemini surfactants, 2(12)-s-2(12), were successfully prepared and characterized, and their monolayer films investigated by the measurement of surface pressure-area (π-A) and surface pressure-time (π-t) isotherms at the air/water interface by a Langmuir film balance. Compared to their monomeric counterparts, their collapse pressure (γ_collapse) is smaller, whilst all the molecular area parameters are larger. The limited area (A_limited) and the initial area (A_initial) of these twin-tailed gemini surfactants change with increasing spacer length s, and the surface pressure decreases with increasing time. It was also found that the higher the initial surface pressure, the larger the attenuation.      

Adsorption and thermodynamic properties of dissymmetric gemini imidazolium surfactants with different spacer length

A series of dissymmetric gemini imidazolium surfactants with different spacer length ([C_mC_sC_nim]Br₂, m + n = 24, m = 12, 14, 16, 18; s = 2, 4, 6) were synthesized and characterized by ¹H NMR and ESI-MS spectroscopy. Their adsorption and thermodynamic properties were investigated by the surface tension and electrical conductivity methods. Consequently, the surface activity parameters (cmc, γ_cmc, π_cmc, pC₂₀, cmc/C₂₀, Γ_max, A_min) and thermodynamic parameters (ΔG_m^θ, ΔH_m^θ, ΔS_m^θ) were obtained. The effects of the dissymmetry (m/n) and the spacer length (s) on the surface activity and micellization process of surfactants have been discussed in detail.     

Synthesis and aqueous solution properties of homologous gemini surfactants with different head groups

A series of homologous gemini surfactants possessing identical hydrophobic chains but different ionic head groups (cationic, anionic, zwitterionic) were synthesized, and their aqueous solution properties were examined. The results showed that the surface activities of gemini surfactants are superior to those of corresponding conventional monomeric surfactants, and molecular arrangements of gemini surfactants at the air-water interface are tighter than those of corresponding conventional surfactants. It was also found that zwitterionic gemini surfactant possesses the highest surface activity among the three surfactants. The behavior at the air-water interface is closely related to the molecular structural features of surfactants, which provide an indication for synthesizing highly-efficient surfactants.      

Thermophysical properties of aqueous solutions of the 1-ethyl-3-methylimidazolium tricyanomethanide ionic liquid

Thermophysical behavior of the binary system [water + 1-ethyl-3-methylimidazolium tricyanomethanide ionic liquid (IL)] was thoroughly characterized through systematic measurements of (vapor + liquid) equilibria (water activity a_w), mixing enthalpy, density, viscosity, and refractive index. The measurements were performed in the entire composition range and/or specifically in the highly dilute IL region, at T = 298.15 K or as a function of temperature in the range from (288.15 to 318.15) K. Effective experimental methods minimizing IL sample consumption, using flow arrangements, instrument couplings and high degree of automation were preferably employed. In particular, the a_w determination based on the chilled-mirror dew point technique and implemented by an AquaLab 4TE instrument was identified as a generally superior approach to study VLE of (water + IL) systems. Excess thermodynamic properties (Gibbs free energy, enthalpy, heat capacity, and volume) and property deviations from the linear mixing rule (viscosity, refractive index) were evaluated, Padé approximants being used to correlate adequately their complex composition dependences. The extensive a_w data were processed by a two-step procedure fitting first the temperature dependence at each isopleth and subsequently the composition dependence at each isotherm. Good estimates could be thus obtained for derivative thermal properties (enthalpy, heat capacity). Alternatively, the water activity and excess enthalpy data were correlated simultaneously by a NRTL-type model, providing their compact, thermodynamically consistent and adequate representation. Despite small absolute values of excess Gibbs free energy (G^E), the system is revealed to be highly nonideal, the small G^E resulting from close compensation of its large enthalpy and entropy contributions. Large endothermic effects and an enhanced increase of entropy upon mixing found for this system indicate relative weakness of interactions between unlike molecules and a massive structure breakage in the solution. Positive values of excess volume and negative values of viscosity and refractive index deviations found in the major part of the composition range corroborate this general energetic and structural pattern, although the situation appears to be more complicated in the highly dilute IL region, where these properties congruently exhibit a sign inversion.     

Thermodynamic properties of aqueous mixtures of LiCl and Li2SO4 at different temperatures

Emf measurements were made on the cell without liquid junction: Li?ISE LiCl(m₁), Li₂SO₄(m₂) Ag/AgCl. The performances of the electrode pairs constructed in our laboratory were tested and exhibited near-Nernstian behavior. The mean activity coefficients of LiCl for the system Li⁺?Cl^??SO ₄ ^2? ?H₂O have been investigated by the emf values at temperatures of 0, 15, 35°C and constant total ionic strengths of 0.05, 0.1, 0.5, 1.0, 2.0, 3.0 and 5.0 mol·kg^?1. The activity coefficients decrease with increasing temperature and the ionic strength fraction of Li₂SO₄ in the mixtures. The thermodynamic properties are interpreted by use of Harned's empirical equations and Pitzer's ion interaction approach including the contribution of higher order electrostatic terms. The experimental results obey Harned's rule and are described by using Pitzer equations satisfactorily. The activity coefficients of Li₂SO₄, the osmotic coefficients and the excess free energies of mixing for the system in the experimental temperature range were reported.     

Effects of the location of the nanoclay at the interface on the mechanical properties of a maleic anhydride grafted polypropylene/polyamide 6/organoclay co‐continuous blend

The effects of the location at the interface of an organoclay on the morphology and mechanical properties of a maleated‐polypropylene/polyamide 6 based co‐continuous blend have been studied. The organoclay is located at the interface because the level of interaction with each of the two polymers was similar. The dispersed particle size remained unchanged with organoclay content because the effect of viscosity and coalescence inhibition was offset by the surfactant compatibilization hindering. The Young's modulus remained constant; this behavior is mainly attributed to the inefficient orientation of the nanoclay. The ductility behavior suggests that there is a maximum amount of organoclay that can be located at the interface while retaining its ductile nature. Once this amount has been exceeded, the interface becomes saturated, and the dispersed particles become encapsulated. Encapsulation means that both an inorganic barrier and discontinuity appear, hindering the stress transmission through the interface and leading to fragility. Copyright © 2012 John Wiley & Sons, Ltd.     

Adsorption of oligooxypropylenated amines at the aqueous solution—air interface: Homologous series of piperidine and morpholine derivatives

The surface tension isotherms for pure oligooxypropylenated piperidine and morpholine at the aqueous solution—air interface were determined and interpreted. The surface excess concentration, Γ, the surface area per molecule, A, and the standard free energy of adsorption, ΔG°, were calculated according to a new empirical adsorption equation. The standard free energy contribution for the oxypropylene group (PO) in morpholine derivatives,ΔG° (PO) = −3.34 kJ mol⁻¹, is substantially lower than that for the PO group located in the piperidine derivatives, i.e. ΔG° (PO)= −3.12 kJ mol⁻¹.     

不同电性Gemini表面活性剂界面扩张性质

利用Langmuir槽法研究了含聚氧乙烯醚链中间链的两性Gemini表面活性剂C8E4NC12、阳离子Gemini表面活性剂C12NE3NC12和阴离子Gemini表面活性剂C8E4C8在空气/水表面和癸烷/水界面上的扩张性质,考察浓度对3种Gemini表面活性剂溶液表、界面扩张性质的影响.结果表明,由于分子间存在库仑引力,两性Gemini分子表现出较高的扩张弹性和粘性,且界面扩张性质类似于表面.对于有相同电荷Gemini分子,C8E4C8分子中的刚性苯环导致其疏水长链在表面上的取向不同于C12NE3NC12分子,两者表现出不同的表面扩张性质;而油分子能改变同电荷Gemini分子中长链烷基的取向,造成其界面扩张弹性和粘性远低于表面.提出了不同电性Gemini分子在界面排布的示意图,并利用弛豫过程的特征参数进行了验证.     

Dilational Viscoelasticity of the Zwitterionic Gemini Surfactants with Polyoxyethylene Spacers at the Interfaces

The dilational viscoelasticity of zwitterionic gemini surfactants C₈E_xNC₁₂ with polyoxyethylene spacers at the water-air and water-decane interfaces were investigated by oscillating barriers method. The experiments were carried out at different concentrations with an accessible frequency range of 0.005 to 0.1 Hz. Interfacial tension relaxation method was employed to obtain dilational parameters in a reasonably broad frequency range. Experimental results show that the values of dilational elasticity and viscosity of C₈E_xNC₁₂ are larger than those of common nonionic surfactants, such as T × 100, and the dilational viscoelasticity at the water-decane is close to that at the water-air interface on the whole_. The results may be attributed to Coulombic attraction, and the possible schematic diagrams of adsorbed molecules with different polyoxyethylene spacers at the water-air and water-decane interfaces are proposed. We also analyzed C₈E_xNC₁₂ from the results of relaxation experiments and Cole-Cole plots.