Polyoxyethylene surfactants

Polyoxyethylene Surfactants. Polyoxyethylene-solubilized nonionics (ethoxylates) were iatroduced ia the United States as textile chemicals shordy before 1940. The solubiUty of these compounds derives from recurring ether linkages ia a polyoxyethylene chain... 

Polyall lene Oxide Block Copolymers. The higher alkylene oxides derived from propjiene, butylene, styrene (qv), and cyclohexene react with active oxygens in a manner analogous to the reaction of ethylene oxide. Because the hydrophilic oxygen constitutes a smaller proportion of these molecules, the net effect is that the oxides, unlike ethylene oxide, are hydrophobic. The higher oxides are not used commercially as surfactant raw materials except for minor quantities that are employed as chain terminators in polyoxyethylene surfactants to lower the foaming tendency. The hydrophobic nature of propylene oxide units, —CH(CH2)CH20—, has been utilized in several ways in the manufacture of surfactants. Manufacture, properties, and uses of poly(oxyethylene- (9-oxypropylene) have been reviewed (98). 

The formation of peroxides and formaldehyde in the high-purity polyoxyethylene surfactants in toiletries has been shown to lead to contact dermatitis [31], Peroxides in hydrogenated castor oil can cause autoxidation of miconazole [32], Oxidative decomposition of the polyoxyethylene chains occurs at elevated temperature, leading to the formation of ethylene glycol, which may then be oxidized to formaldehyde. When polyethylene glycol and poloxamer were used to prepare solid dispersions of bendroflumethiazide, a potent, lipophilic diuretic drug, the drug reacted with the formaldehyde to produce hydroflumethiazide [33],... 

Cheguillaume, G., Buchmann, W., Desmazieres, B., Tortajada, J. (2004). Liquid chromatography-mass spectrometry hyphenation for exhaustive and unambiguous characterization of polyoxyethylene surfactants. Chromatographia 60(9/10), 561-566. 

The classical model, as shown in Figure 1, assumes that the micelle adopts a spherical structure [2, 15-17], In aqueous solution the hydrocarbon chains or the hydrophobic part of the surfactants from the core of the micelle, while the ionic or polar groups face toward the exterior of the same, and together with a certain amount of counterions form what is known as the Stern layer. The remainder of the counterions, which are more or less associated with the micelle, make up the Gouy-Chapman layer. For the nonionic polyoxyethylene surfactants the structure is essentially the same except that the external region does not contain counterions but rather rings of hydrated polyoxyethylene chains. A micelle of... 

Emerest -glycerol ester surfactant [SURFACTANTS] (Vol 23) -polyoxyethylene surfactant [SURFACTANTS] (Vol 23)... 

Base-catalyzed ethoxylation of aliphatic alcohols, alkylphenols. and fatty acids can be broken down into two stages formation of a monocthoxy adduct and addition of ethylene oxide to the monoadduct to form the polyoxyethylene chain. Polyoxyethylene surfactants include alcohol ethoxyiates and akylpheno] ethoxyiates. 

Some carboxylate surfactants, such as long-chain fatty acids or their anionic esters with Coenzyme A, are precipitated in the presence ( fCSmd M + (Constantinides and Steim, 1986). Measurements of CMC in the presence of divalent ions should be avoided since the insoluble surfactant could introduce serious artifacts. Traces of transition-metal ions can catalyze autooxidation of some polyoxyethylene surfactants. In a recent article by Xiao (Xiao, 2006), interactions between anionic surfactant (SDS) micellar solutions and several familiar metal salt solutio b. 

Cassidy and Niro [13] have applied high-speed liquid chromatography combined with infrared spectroscopy to the analysis of polyoxyethylene surfactants and their decomposition products in industrial process waters. Molecular sieve chromatography... 

Mitchell, D.J., Tiddy, G.J.T., Warring, L., Bostock, T. and Me Donald, M.P. (1983) Phase behavior of polyoxyethylene surfactants with water, mesophase structures and partial miscibility (cloud points). /. Chem. Soc. Faraday Trans. I, 79(4), 975-1000. 

The effect of the oily component on the phase behavior of o/w ME-forming systems formulated with nonionic surfactants was reported [23].The authors showed that it is possible to formulate cosurfactant-free o/w ME systems suitable for use as drug delivery vehicles using either polyoxyethylene surfactants or amine-A-oxide surfactants. The major advantage of these ME systems is their ability to be diluted without destroying their integrity however both classes of surfactants were shown to be sensitive to electrolytes. 

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