Mixtures of nonionic surfactants

A mixture of nonionic surfactants, consisting of a capped alkylphenol ethoxylate or an ethoxylated higher aliphatic alcohol... 

The cloud point of a mixture of nonionic surfactants is intermediate between the pure nonionic surfactants involved (95.99) The cloud point of a dilute nonionic surfactant solution increases upon addition of ionic surfactant (95.98—104). The coacervate phase forms because of attractive forces between the micelles in solution. The incorporation of ionic surfactant into the nonionic micelles introduces electrostatic repulsion between micelles, causing coacervate phase formation to be hindered, raising the cloud point. 

Several prespotter formulations are disclosed in the patent literature. Acidic compositions that contain a mixture of nonionic surfactants and hydrotropes [163], thickened alkaline products with hypohalite bleaches [164,165], and enzyme-containing formulas [ 166] have all been developed for use as prespotters. Although... 

Surfactants are able to extract organic additives from plastic materials. Cremo-phor EL is a mixture of nonionic surfactants used as a vehicle in various intravenous injections. It is incompatible with polyvinyl chloride containers due to extraction of phthalates from the polymer (Parfitt, 1999 Nuijen et al., 1999, 2001). Because even trace amounts of organic molecules may act as photosensitizers in the formulation, extraction of organic additives from the container should be avoided (see Section 14.3). 

Several other mechanisms have been proposed to explain the dynamics of spontaneous emulsification. Direct observation by using phase contrast and polarizing microscopy showed that in some cases vesicles (closed bilayers) are produced in the oil phase near the interface with the water. These vesicles tend to explode , thereby pulverizing oil droplets into the aqueous phase. The above structures can be produced, for example, by using a mixture of nonionic surfactant (alcohol ethoxylate) and a long-chain alcohol such... 

TLC may be used to separate mixtures of anionics, cationics and nonionics, prior to FAB analysis, which is carried out on silica removed from appropriate regions of the plate. Mixtures of nonionic surfactants may be separated and analysed on-line by SFC-MS or LC-MS, or GC-MS for the low-EO species. 

Aqueous Solutions of Mixtures of Nonionic Surfactants as Environment-Friendly Lubricants... 

Conversely, for small volume changes of a hexane/water system with binary mixtures of nonionic surfactants, Mulqueen and Blankschtein [48] found no change in interfacial tension. It should be noted in this case, though, that the difference in phase volumes is probably not enough to show the effect described above, which is only marked when there is a difference of at least several orders of magnitude between phase volumes. 

Semi-solid emulsions or creams should have both physical and chemical stability, acceptable cosmetic effect and optimum environment for the active ingredient to reach the skin. The most commonly used creams are those based on a mixture of an ionic surfactant, such as cetrimide, with cetostearyl alcohol (e.g. in Cetavlon cream) or a mixture of nonionic surfactant (such as Cetomacrogel, an alcohol ethoxylate) with cetyl or stearyl alcohol [52]. 

It is believed that the formation of a microemulsion can enhance detergent action since the oil-water interfacial tension can be lowered considerably, which facilitates solubilization of oily dirt particles by surfactant. The microemulsion is of Winsor type III (Section 3.13.2), with small amounts of surfactant forming a middle phase microemulsion in equilibrium with excess oil and water. The oil-water interfacial tension is a minimum at the phase inversion temperature (PIT) of an oil-water-surfactant system, so it is desirable to optimize the properties of the detergent mixture so that the system is close to the PIT at the washing temperature. Microemulsions made from mixtures of nonionic surfactants are used in hard surface cleaning products. Usually they are sold in concentrated form and diluted prior to use. 

The theoretical aspects of the kinetics of two-component micelles based on the stepwise association model were later extended to high surfactant concentrations. - This model applies to binary mixtures of nonionic surfactants as well as to one ionic surfactant, the surfactant ion and its counterion then being the two components of the system. 

Chem. Descrip. mixture of nonionic surfactants Uses Surfactant for emulsion polymerization... 

Puwada, S., Blankschtein, D. Theoretical and experimental investigations of micellar properties of aqueous solutions containing hinary mixtures of nonionic surfactants. J. Phys. Chem. 1992, 96(13), 5579-5592. 

Szymanski, A., Z. Lukaszewski, Indirect tensammetric method for the determination of nonionic surfactants. Part 1 General properties of the analytical signal. Part 2 Investigation and improvement of tolerance to manmade anionic surfactants. Part 3 Properties of the analytical signal of mixtures of nonionic surfactants. Anal. Chim. Acta, 1992, 260, 25-34 1993, 273, 313-321 1994,295, 77-86. 

The critical micelle concentrations of mixtures of POE nonionic surfactants are of particular interest, since the synthesis of such materials on a commercial basis will always produce a rather broad range of POE chain lengths. Because they contain no electrostatic contribution to the free energy of micelle formation, they can be treated theoretically with a simpler relationship between composition and cmc. In a mixture of nonionic surfactants in which the average POE chain lengths are approximately the same and the hydrocarbon chains different, there was a smooth decrease in the cmc of the mixture as the mole fraction of the more hydrophobic material (lower cmc) was increased, reminiscent of the surface tension-mole fraction curves found for miscible organic materials mixed with water. 

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