Micelles water-wetting

Figure 10.19. Solid surface drying by water solubilization in reversed micelles (a) wet metal surface (b) drying surfactant micelles begin to absorb water (c) dry surface and solubilized waters.

The model has been successfully used to describe wetting behavior of the microemulsion at the oil-water interface [12,18-20], to investigate a few ordered phases such as lamellar, double diamond, simple cubic, hexagonal, or crystals of spherical micelles [21,22], and to study the mixtures containing surfactant in confined geometry [23]. 

These rate effects are consistent with a wet micellar surface and the water molecules associated with the micelle seem to have reactivities which... 

The rate of attack of water upon the tri-/>-anisylmethyl cation is unaffected by binding of this cation to anionic micelles of sodium dodecyl sulfate (SDS) (Bunton and Huang, 1972) and equilibrium constants for aldehyde hydration are only slightly reduced by binding to micelles (Albrizzio and Cordes, 1979). These observations are also consistent with substrate binding at a wet micellar surface rather than in the interior of the micelle. 

First, micelles have very loose, mobile, structures and there are considerable entropy costs in a concerted reaction. These costs are much less serious in enzymic systems where conformation at the active site is tailor-made to fit the transition state. Secondly, the sites of micellar reactions are very wet and omnipresent water molecules are available to transfer protons. 

Alternatively, the Rh/15-catalysed hydroformylation of 1-tetradecene may proceed in wet micelles 478 (which are water-permeated micelles) or in reversed micelles155,389,406 with solubilisation of an aqueous microdroplet of the Rh/15 catalyst in the organic bulk phase [cf. Figure 4 (A)]. 

This experiment introduces the use of a probe molecule to explore the microenvironment within a micelle. The results in this case show the environment to be quite wet, but this observation alone does not tell us where either the benzene or the water is. Any one of the... 

The solubility of the sodium salt of (meta-sulfonatophenyl)diphenylphos-phine, TPPMS in water is approximately 12 g/L at room temperature.5 It dissolves slightly in cold ethanol, but is soluble at elevated temperatures. It is virtually insoluble in acetone and aliphatic, aromatic, or chlorinated hydrocarbons, but is soluble at room temperature in tetrahydrofuran. The compound crystallizes with two waters of crystallizations however, the anhydrous form can also be obtained.3 Dry TPPMS is stable to air but is oxidized rapidly when wet, especially in basic aqueous solutions. It is a highly surfactant compound and forms aggregates and micelles in neutral aqueous... 

Crystalline polymers appear to be the most studied by ESR techniques. The model wiiich seems to emerge from these results is, in fact, a variant of a model proposed over twenty years ago by Cumberbirch and associates (Shirley Institute Memoirs) to explain the tenacity of wet raycm monofilaments. Briefly, Cumberbirch, et al propose a fringe-micelle structure in which the fringe r ons, swollen by water, are assumed to obey rubber elasticity theory. These fringe reglcms are, of course, the more accessble (to water), more disordered, r ons of the semicrystalline structure. 

A certain amount of potassium bromide remains trapped in the reverse micelles formed by THA cations and heteropoly anions after the transfer of potassium salts of HPT s with THABr. In wet toluene solution both ions are hydrated inside the reverse micelles. As the water is removed bromide ions coordinate to transition metal on HPT and potassium ions form ion pairs with HPT s. 

Cationic surfactants adsorb strongly on clay surfaces by cation exchange. The fatty tails of these adsorbed surfactants impart oil-wetness to the clay surfaces and shield the clays from direct contact with water. This shielding has an obvious stabilizing effect however, this change in wettability often results in undesirable side effects, such as a decrease in oil relative permeability. Moreover, because of the possibility of multilayered adsorption (formation of surface micelles), a high surfactant concentration is required to satisfy the cation exchange capacity of the clays, which can make such treatments rather expensive. 

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