Solubilization in Lubrication

Solubilization of water. Detergency is defined as the ability of surfactant molecules to solubilize water molecules or polar substances in soft-core and hardcore RMs. Thus, micellization and solubilization are competitive processes. Any solubilized probe molecule causes a decrease in the CMC. Solubilization describes the dissolution of a solid, liquid or gas by an interaction with surfactant molecules. Addition of water has a dramatic effect on surfactant aggregation in hydrocarbons because hydrogen bonding has an appreciable stabilizing effect on reverse micelles. Solubilization for reverse micelles is phenomenologically similar to the adsorption processes (Eicke and Christen, 1978 Kitahara, 1980 Kitahara et al., 1976 Singleterry, 1955). 

The size and characteristics of soft-core reverse micelles are critically dependent upon the water content of the solution. The water present tends to accumulate with the soft-core to form an isolated pool which may exhibit unique properties. At a low ratio of water to surfactant (Wo 10) the activity of the water is greatly diminished as compared with that of bulk water. The quantity of water 

Micellar solubilization of water by surfactants having different polar groups follows the order  

For small amounts of solubilized water, as a polar additive, the stability of the micelle is markedly increased, as shown by a decrease in the CMC. On the other hand, large amounts of water as a polar additive decrease the stability of the micelle. It is known that a solution of AOT in iso-octane solubilized up to 50 moles of water per mole of surfactant. As the concentration of water increases, the isotropic reverse micellar solution changes to a water-in-oil microemulsion. A clear understanding of the complex analyte-micelle-water pool interactions, especially analyte concentration and pH at the head group interfacial region, is under intensive study (Cline Love and al., 1984 Little and Singleterry, 1964 Luisi and Straub, 1984 Mclntire, 1990). 

The characteristics of the water pool of reverse micelles has been explored by H, 23Na, 13C, 3IP-NMR spectroscopy. Since the initial association process in RMs is not totally understood, and because of the low CMC, aggregation studies from NMR are rather scarce. Direct determination of a CMC in the diethyl hexyl phosphate /water/benzene system (at Wo = 3.5) was possible because the chemical shift of 31P in phosphate groups is very sensitive to hydration effects. The structure and state of water in RMs and particularly at low water content has received considerable attention. The proton chemical shifts have been explored in AOT/water/heptane, methanol, chloroform, isooctane and cyclohexanone. The water behavior in small reverse micelles is close to that of the corresponding bulk ionic solution. Until now, the effect of a solute on micellar structure was not well 

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Uses Emulsifier and solubilizer in lubricants, mold releases and plasticizers for synthetic fabrics and plastics, food-pkg. adhesives and pulp/paperboard Regulatory Kosher US FDA 21CFR 175.105... 

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