Surfactants physico-chemical properties

Due to their distinctive physico-chemical properties, non-ionic surfactants are applied in the fields of industry, processing technology and science, wherever their interfacial effects of detergency, (de)foaming, (de)emulsification, dispersion or solubilisation can enhance product or process performance. The characteristics of non-ionic surfactants that make them beneficial for detergents include their relatively low ionic sensitivity and their sorptive behaviour [17]. 

DTDMAC was the first widely used cationic surfactant produced at the industrial scale since the 1960s. Its main application was as a fabric softening active agent. Due to its physico-chemical properties, largely determined by the positively charged head group and the long alkyl chains, it adsorbs onto fabrics and makes textiles feel soft. 

Taking into consideration its physico-chemical properties, removal efficiencies, low biodegradability, predicted environmental levels, toxicity, and the need to provide sufficient safety margins for aquatic organisms, the demand for alternative cationic surfactants arose. Since 1991, DTDMAC has been replaced in some European countries due to producer s voluntary initiatives with new quaternary ammonium compounds, the esterquats. These contain an ester function in the hydrophobic chain (Table 1.3) that can be easily cleaved, releasing intermediates that are susceptible to ultimate degradation [24-26]. The effects of the phasing-out and replacement of DTDMAC can be demonstrated by the results of a Swiss study, where the surfactant... 

Van Os NM, Haak JR, Rupert LAM. Physico-chemical properties of selected anionic, cationic and nonionic surfactants. Elsevier Amsterdam 1993. 

Salager JL (1977) Physico-chemical properties of surfactant-oil-water mixture phase behavior, microemulsion formation and interfacial tension. PhD Dissertation, University of Texas at Austin... 

N. M. van Os, J. R. Haak, and L. A. M. Rupert, eds., Physico-Chemical Properties of Selected Anionic, Cationic, and Nonionic Surfactants, Elsevier, Amsterdam, the Netherlands, 1993. 

Rodriguez Patino, J.M., Rodriguez Nino, M.R., Sanchez, C.C. (2007). Physico-chemical properties of surfactant and protein films. Current Opinion in Colloid and Interface Science, 12, 187-195. 

Through a co-assembling route, mesostructured lamellar molybdenum sulfides are formed hydrothermally at about 85 °C using cationic surfactant molecules as the templates. The reaction temperature and the pH value of the reaction system are important factors that affect the formation of the mesostructured compounds. The amount of the template and that of the S source are less critical in the synthesis of the compounds. For the three as-synthesized mesostructured materials, the interlayer distance increases linearly with the chain length of the surfactant. Infrared and X-ray photoelectron spectroscopy reveals that the individual inorganic layers for the three compounds are essentially the same both in composition and in structure. The formal oxidation state of the molybdenum in the materials is +4 whereas there exist S2 anions and a small amount of (S-S)2 ligands in the mesostructures. The successful synthesis of MoS-L materials indicates that mesostructured compounds can be extended to transition metal sulfides which may exhibit physico-chemical properties more diverse than non-transition metal sulfides because of the ease of the valence variation for a transition metal. 

The many remarkable physico-chemical properties of aqueous surfactant systems, as well as their numerous practical applications, can be referred to the tendency of the nonpolar groups to avoid contact with water at the same time as the polar part tends to be strongly hydrated. The adsorption of surfactants at interfaces between aqueous solutions and air, another liquid phase or a solid is one consequence of this, the extensive aggregation into various types of large aggregates termed micelles — from lat. micella meaning small bit — and liquid crystalline phases is another. 

Physico-Chemical Properties of Surfactant Solutions. Thermodynamic and... 

The very complex variation of the amount solubilized, as well as physico-chemical properties, with chemical structure of solubilizate and surfactant as well as with surfactant concentration cannot be adequately discussed solely in terms of the energetical conditions of the solubilizate in the micelles. Thus one should also consider the conditions in the phase which separates out at the solubilization limit this is in most cases a liquid crystalline phase. A fundamental basis for a proper understanding of solubilization in surfactant systems is, therefore, a detailed information on phase equilibria in three-component systems surfactant-solubilizate-water. Due in particular... 

The strong cooperativity of amphiphile association into micelles is well established and for long-chain surfactants it is often a good approximation to consider micelle formation as analogous to a phase separation. Even if the concentration dependence of many physico-chemical properties, within experimental accuracy, is in concor-... 

Shinoda, K., et al. Colloidal Surfactants. Some Physico-Chemical Properties. New York Academic 1963... 

Many pharmaceutical preparations contain multiple components with a wide array of physico-chemical properties. Although CZE is a very effective means of separation for ionic species, an additional selectivity factor is required to discriminate neutral analytes in CE. Terabe first introduced the concept of micellar electrokinetic capillary chromatography (MEKC) in which ionic surfactants were included in the running buffer at a concentration above the critical micelle concentration (CMC) [17], Micelles, which have hydrophobic interiors and anionic exteriors, serve as a pseudostation-ary phase, which is pumped electrophoretically. Separations are based on the differential association of analytes with the micelle. Interactions between the analyte and micelles may be due to any one or a combination of the following electrostatic interactions, hydrogen bonding, and/or hydro-phobic interactions. The applicability of MEKC is limited in some cases to small molecules and peptides due to the physical size of macromolecules... 

Bouquillon S (2011) D-Xylose and L-arabinose-based surfactants synthesis, reactivity and physico-chemical properties. C R Chim 114 716-725... 

Polyelectrolyte block copolymers combine structural features of polyelectrolytes, block copolymers, and surfactants. It is thus not surprising that they possess quite unusual and unique properties which make them a fascinating and challenging subject for researchers. Many of these properties are taken advantage of in technological applications and play an important role in physico-chemical properties of biological cell structures. This has motivated a comprehensive investigation so that today a much clearer picture of the behavior of polyelectrolyte block copolymers has developed. 

Umehara, K. (1992) Washing behaviour of alpha-sulpho fatty acid methyl esters and their physico-chemical properties. Proceedings 3rd CESIO International Surfactants Congress, vol. D, pp. 234 2. 

Washes. Several types of solutions or liquids can be used to collect handwash samples, including various types of aqueous surfactant solutions, and neat isopropanol or ethanol. The physico-chemical properties of the pesticide should guide selection of the rinse solvent, especially the octanol-water partition coefficient... 

Tomas, A., J.-L. Courthadon, D. Paquet, and D. Lorient, Effect of Surfactant on Some Physico-Chemical Properties of Dairy Oil-in-Water Emulsions, Food Hydrocoll. 8 543-553 (1994). 

A simple classification of surfactants, based on the nature of the hydrophilic group, is commonly used, with four main classes being distinguished anionic cationic amphoteric and nonionic. A useful technical reference here is McCutcheon [3], which is produced annually to update the list of available surfactants. A recent text by van Os et al. [4], hsting the physico-chemical properties of selected anionic, cationic and nonionic surfactants, has been published by Elsevier. 

Both, alkyl phosphates and alkyl ether phosphates are made by treating the fatty alcohol or alcohol ethoxylates with a phosphorylating agent, usually phosphorous pentoxide, P4OJQ. The reaction yields a mixture of monoesters and diesters of phosphoric acid, with the ratio of the two esters being determined by the ratio of the reactants and the amount of water present in the reaction mixture. The physico-chemical properties of the alkyl phosphate surfactants depend on the ratio of the esters. Phosphate surfactants are used in the metal-working industry, due to their anticorrosive properties. 

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