Polyoxyethylene dehydration

For pure nonionic EO adducts, increase in the number of oxyethylene groups in the molecule results in a decrease in the tendency to form micelles and an increase in the surface tension of the solution at the critical micelle concentration (1 ) (l. ) This change in surface activity is due to the greater surface area of the molecules in the adsorption layer and at the micellar surface as a result of the presence there of the highly hydrated polyoxyethylene chain. The reduction in the tendency to form micelles is due to the increase in the free energy of micelle formation as a result of partial dehydration of the polyoxyethylene chain during incorporation into the micelle ( 1 6) (17). 

Propylene Glycol, Sorbitol, and POE Sorbitol Esters Propylene glycol esters are more lipophilic than the corresponding glycerol esters sorbitol esters are more hydrophilic (unless dehydrated in course of manufacture). Polyoxyethylenation of sorbitol (and anhydrosorbitol produced during manufacture) gives wide range of solubilities and hydrophilic-lipophilic balances to products. 

With rising temperature the volume of the aqueous phase grows, the micelles swell until suddenly, at the so-called phase inversion temperature, the oil phase has the larger volume. This effect is explained by the polyoxyethylene chains dehydrating as the temperature rises. The hydrophilic/hydrophobic balance of the molecule is thereby altered and the solubility in the oil phase grows. When concentration is great enough, micelles are formed in the oil phase and water is solubilised. If the two phases do not exist as stratified layers but as emulsion a... 

Non-ionic Surfactants. These surfactants do not present the Krafft phenomenon. However, a nonionic micellar solution becomes turbid and separates in two phases when the temperature is raised. This is the clouding phenomenon. The polyoxyethylene chain, the polar part of most non-ionic surfactants, is progressively dehydrated as the temperature raises. Losing water molecules, the polyoxyethylene ehain becomes less polar and, at a particular temperature, a turbidity, the clouding, appears. This temperature is called the cloudpoint of the nonionic surfactant solution. Above the cloud point, the nonionic micellar solution separates in an aqueous phase saturated by the nonionic surfactant, and an organic phase saturated by water and containing the major part of the surfactant. 

The answer probably is that ion associations give rise to a rather different and more complex phenomenon than only dehydration of the polyoxyethylene chain in water solution. In addition, ion-clustering effects in the poly(ethylene oxide) molecule in water-salt solutions probably occur even in dilute solutions. 

The cloud point and the surfactant-water systems have been extensively studied for nonfluorinated nonionic surfactants. The phase separation at the cloud point has been explained by dehydration of the polyoxyethylene chain of the nonionic surfactant with increasing temperature [107]. The dehydration theory has... 

These types of surfactants become lipophilic with increasing temperature because of dehydration of the polyoxyethylene chains. At low temperature, the surfactant monolayer has a large positive spontaneous curvature forming oil-swollen micellar solution phases (or OAV microemulsions), which may coexist with an excess oil phase. At high temperatures, the spontaneous curvature becomes negative and water-swollen reverse micelles (or W/O microemulsions) coexist with excess water phase. At intermediate temperatures, the hydrophile-lipophile balance (HLB) temperature, the spontaneous curvature becomes close to zero and a bicontinuous, D phase, micro-... 

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