Mixed adsorption and surface tension prediction of nonideal ternary surfactant systems

To deal with the mixed adsorption of nonideal ternary surfactant systems, the regular solution approximation for nonideal binary surfactant systems is extended and a pseudo-binary system treatment is also proposed. With both treatments, the compositions of the mixed monolayer and the solution concentrations required to produce given surface tensions can be predicted based only on the -LogC curves of individual surfactants and the pair interaction parameters. Conversely, the surface tensions of solutions with different bulk compositions can be predicted by the surface tension equations for mixed surfactant systems. Two ternary systems: SDS/Hyamine 1622/AEO₇, composed of homogeneous surfactants, and AES/DPCl/AEO₉, composed of commercial surfactants, in the presence of excess NaCl, are examined for the applicability of the two treatments. The results show that, in general, the pseudo-binary system treatment gives better prediction than the extended regular solution approximation, and the applicability of the latter to typical anionic/cationic/nonionic nonideal ternary surfactant systems seems to depend on the combined interaction parameter, : the more it deviates from zero, the larger the prediction difference. If 0, good agreements between predicted and experimental results can be obtained and both treatments, though differently derived, are interrelated and tend to be equivalent.Poster presentation at the 14th SIS conference, June 2002, Barcelona     

Monolithic Gels of Silica and Nonionic Surfactant: Matrices for the Dispersion of Metal Ions

The formation of homogeneous monolithic gels by the addition of TEOS to acidic amphiphilic solutions has been investigated for a range of nonionic surfactants, and the relationships between solution composition and gelation examined. Using the surfactant solutions as a means of pre-doping the matrices with high concentrations of manganese nitrate gave gels which could be calcined to 400°C with little or no segregation of manganese oxide observed by X-ray diffraction. X-ray absorption spectroscopy has shown that the ligand environment of manganese in the silica-surfactant matrices differs from that in gels derived from ethanol solutions, and that most of the manganese in the calcined gels remains in a disordered environment.     

Lower critical solution temperature (LCST) and theta temperature of aqueous solutions of nonionic surface active agents of various polyoxyethylene chain lengths

Cloud points of aqueous solutions of homogeneous poly(oxyethylene)dodecyl ether derivatives (C₁₂(OE)_n: n=2–8) and the apparent theta temperatureT ^ap were determined from the abrupt changes in optical transmittance and the temperature dependence of the second virial coefficient obtained by light scattering measurements. It was found that the lower critical solution temperature (LCST) shifts to a lower temperature and lower concentration as the number of oxyethylene units in a molecule decreases. Because of this behavior of LCST, the modified Flory-Schultz plot of phase separation was applied to the present nonionic surfactant-water system, and its theta temperature obtained. The dependence ofT ^ap on the number of oxyethylene units suggests that the polyoxyethylene chain has different effects on the solubility of C₁₂(OE)_n in water forn less than or equal to 3 from those forn greater than or equal to 4.     

胶束介质中的Wittig—Horner反应研究

近年来手性胶束及混合胶束的出现,使得胶束在模拟酶研究方面取得了长足的进展。胶束作为酶的一个简单模型,可催化多种复杂有机反应,已有的胶束催化有机反应大多数与生化反应有关,如酯的水解反应等,胶束催化碳负离子反应的研究却很少,非离子型胶束催化的碳负离子反应就更少,本文报导用聚乙二醇类表面活性剂形成的胶束来     

非离子乳化剂对淀粉接枝丙烯酰胺、丙烯酸反相乳液聚合反应的作用

接枝共聚;非离子乳化剂对淀粉接枝丙烯酰胺、丙烯酸反相乳液聚合反应的作用     

Formation of Nonspherical Particles with Uneven Surface in Emulsion Copolymerization of Styrene and Methacrylic Acid with Nonionic Emulsifier

Summary: Emulsion copolymerization of styrene and methacrylic acid with nonionic emulsifier and potassium persulfate as initiator gave nonspherical copolymer particles having uneven surface. The formation was based on the coagulation of byproduct nano-sized (ca. 35 nm) particles, which were formed throughout the copolymerization until monomer phase disappeared, onto main submicron-sized (234 ∼ 445 nm) particles.     

Investigation on the basic hydrolysis of crystal violet in mixed reverse micelles formed with AOT and nonionic surfactants

 The kinetics and thermodynamics of the basic hydrolysis of crystal violet (CV) in mixed reverse micelles formed with anionic surfactant AOT and nonionic surfactants have been investigated. It was found that the mixed reverse micelles had inhibitory effects on CV hydrolysis compared with the normal aqueous solution, and the equilibrium constant K of the reaction in mixed reverse micellar systems is smaller than that in pure water. The influence of water content and surfactant composition in reverse micelles on the second-order rate constant k ₁ of the positive reaction, on the first-order rate constant k _-1 of the reverse reaction, as well as on the equilibrium constant K of the reaction has been studied, and the results obtained were interpreted in terms of the nature of surfactants and the properties of microenvironment where the reaction took place. Received: 24 October 1997 Accepted: 18 March 1998     

Empirical equations of state for adsorption layer: Alkylthiopolyoxyethylene glycols

Surface tension isotherms ofn-alkylthiopolyoxyerhylene glycols:n-C _x H_2x+1S(CH₂CH₂O) _y H, wherex=5 to 8,y=3 or 4, were approximated with orthogonal polynomials to get good quality values of surface pressure (II) and molar area of the adsorbed layer (). The modified Volmer (*(–₀)=Z*R*T) van der Waals and virial equations of state were used to correlate and in terms of real two-dimensional gas. The combination of Volmer and van der Waals equations of state made it possible to determine the interaction energy, , which was prescribed to cohesion of hydrophobic chains in the adsorption layer. The value of for the amphiphiles in question was in the range 0.97–1.91R*T and the average contribution per methylene group was ca. 0.21R*T.The Lennard-Jones potentials calculated from second virial coefficient were of the same range as , but no clear relation was found between their values and number of structure elements of the alkylthiopolyoxyethlene glycols.Presented during 7th International Conference: Surface and Colloid Science, July 7–13, 1991, Compiegne, France     

Partial molal volumes and adiabatic compressibilities of dodecylpolyoxyethylene glycol monoethers in water at 5, 25, and 45°C

Density and ultrasonic velocity measurements were made on a series of dilute aqueous solutions ofn-C ₁₂ H ₂₅ O (CH ₂ CH ₂ O) _n H (n=6,7 and 8) at 5, 25, and 45°C. The partial molal volumes (V) and adiabatic compressibilities (K)of the solutes were independent of the concentration in the micellar solutions. This finding suggests that the mode of aggregation does not change over the concentration range studied. Larger V and K were found for the CH ₂ CH ₂ groups in micelles than in water, and the micellar core was shown to be liquidlike. The V and K of the monomeric surfactants could not directly be measured because of the very low c.m.c.'s. The infinite dilution values V^° and (K^°) were, however, estimated from the V^° and K^° for the constituent groups on the basis of additivity. Thus, sharp increases were found in both V and K on micellization, which was interpreted in terms of dehydration effects.     

Prediction on Critical Micelle Concentration of Nonionic Surfactants in Aqueous Solution： Quantitative Structure-Property Relationship Approach

IntroductionCriticalmicelleconcentration (cmc)ofsurfactantsinaqueoussolutionisoneofthemostusefulparametersforcharacterizingthepropertiesofsurfactants.Overaverynarrowconcentrationrangearoundthecmctransitionsoftheexistenceofsurfactantsoccurfrommonomer ,premicel lartomicellar .Andcompanyingthesetransitions ,manyotherimportantpropertiesofsurfactantsolution ,suchassurfacetension ,interfacialtension ,conductivity ,osmoticpressure ,detergency ,emulsification ,foamingandsoon ,alsochangesharplyatthepoi…