Ethylene oxide surfactants and

Vasilescu, M. Caragheorgheopol, A. Caldararu, H. Aggregation numbers and micro structure characterization of self-assembled aggregates of poly(ethylene oxide) surfactants and related block-copolymers, studied by spectroscopic methods. Adv. Colloid Interf Sci. 2001, 89, 169-194. 

It was shown in the early 1990s that nanoscale porosity of silicas can conveniently be generated in a predictable way using smfactant micelles as templates." This approach can be used to form cylindrical pores (diameter 2-30 nm), " spherical pores (diameter 3-27 nm), and other periodic porous structures. Surfactants that are suitable as mieellar templates include alkylammonium surfactants, oligomeric alkyl-poly(ethylene oxide) surfactants, and block copolymers with poly (ethylene oxide) block(s). " The micelle-templating approach has been extended to some other compositions relevant for the manufacture of on-chip insulations, including polymethylsilsesquioxane (formula unit SiOi 5-./2(CH3)(0H),) and... 

Ethylene oxide [75-21-8] was first prepared in 1859 by Wurt2 from 2-chloroethanol (ethylene chlorohydrin) and aqueous potassium hydroxide (1). He later attempted to produce ethylene oxide by direct oxidation but did not succeed (2). Many other researchers were also unsuccesshil (3—6). In 1931, Lefort achieved direct oxidation of ethylene to ethylene oxide using a silver catalyst (7,8). Although early manufacture of ethylene oxide was accompHshed by the chlorohydrin process, the direct oxidation process has been used almost exclusively since 1940. Today about 9.6 x 10 t of ethylene oxide are produced each year worldwide. The primary use for ethylene oxide is in the manufacture of derivatives such as ethylene glycol, surfactants, and ethanolamines. 

Commercial mixtures of surfactants consist of several tens to hundreds of homologues oligomers and isomers. Their separation and quantification is complicated and a cumbersome task. Detection, identification and quantification of these compounds in aqueous solutions, even in the form of matrix-free standards, present the analyst with considerable problems. The low volatility and high polarity of some surfactants and their metabolites hamper the application of gas-chromatographic (GC) methods. GC is directly applicable only for surfactants with a low number of ethylene oxide groups and to some relatively volatile metabolic products, while the analysis of higher-molecular-mass oligomers is severely limited and requires adequate derivatisation. 

Steric stabilisers are usually block copolymer molecules (e.g. poly (ethylene oxide) surfactants), with a lyophobic part (the anchor group) which attaches strongly to the particle surface, and a lyophilic chain which trails freely in the dispersion medium. The conditions for stabilisation are similar to those for polymer solubility outlined in the previous section. If the dispersion medium is a good solvent for the lyophilic moieties of the adsorbed polymer, interpenetration is not favoured and interparticle repulsion results but if, on the other hand, the dispersion medium is a poor solvent, interpenetration of the polymer chains is favoured and attraction results. In the latter case, the polymer chains will interpenetrate to the point where further interpenetration is prevented by elastic repulsion. 

There is a vast body of diblock copolymer studies since block choice can be such that they resemble amphiphilic surfactants. For the sake of brevity, we will skip them. Instead, we present an interesting case of triblock copolymers of poly(ethylene oxide), PEO, and poly(propylene oxide), PPO, commonly known by one of its trade names, Pluronics [117]. They have been used as non-ionic surfactants for a variety of applications such as in emulsification and dispersion stabilization. In aqueous solutions, these copolymers form micelles, and there exists a well-defined critical micelle concentration that is experimentally accessible. Several groups have investigated colloidal suspensions of these polymers [118-122], The surface properties of the adsorbed monolayers of the copolymers have been reported with respect to their structures and static properties [123-126]. 

Structure-activity relationships between several nonionic surfactants and three water-soluble herbicides have been studied (58). In general it has been shown that the herbicide, the surfactant concentration, the hydrophilic constitution (ethylene oxide content), and the hydrophobic portion of the molecule all markedly influence toxicity. 

In France, however, there was no vertical integration between the great national chemical industry and the surfactant sector. Producers of the latter had to find the necessary feedstock—whether ethylene oxide, alkylphenols, fatty acids or higher alcohols— from rival companies, while for instance a medium-sized company like Berol Chemie in Sweden, recently acquired by Nobel Industries, had its own source of ethylene oxide, amines and nonylphenol in Stenungsund to feed its surfactants division. 

Ethylene and Propylene Oxide. Ethylene oxide (EO) and propylene oxide (PO) are commonly used raw materials for surfactant production. Both are highly reactive compounds that will react with alcohols, amines, carboxylic, and water. EO and PO will also self-polymerize to form high-molecular-weight polymers. Ethylene... 

The data entirely support the previous conclusions concerning the retention mechanism of surfactants on alumina. Moreover, Eqs. 3 and 4 indicate that alumina is an excellent support for the separation of tetrabutylphenyl ethylene oxide oligomers according to the number of ethylene oxide groups and the position of the alkyl substituents in one run. The efficiency of alumina support for the separation of positional isomers was also established with HPLC-mass spectrometry (HPLC-MS). ... 

Spans, Tritons, and Tweens are series of nonionic surfactants. Some of these products do not represent specific chemical compounds but rather mixtures of similar compounds having different number of ethylene oxide segments and/or different lengths of hydrocarbon chain, and the apparent adsorption isotherm is a result of interaction of particular components of the mixture in solution and on the surface. 

Surfactant molecules by definition have polar groups such as ions or ethylene oxide chains and nonpolar groups such as hydrocarbon or fluorocarbon chains. When they are added to water, aggregation normally occurs at fairly low concentrations to minimize the area of contact between the nonpolar groups and water. For low temperatures and molecules with long, straight hydrocarbon chains, separation into a crystalline solid phase and a dilute aqueous solution of molecularly... 

Alkyl ethylene oxide condensates and nonionic polymers such as poly(vinyl alcohol) or poly(propylene oxide)-poly(ethylene oxide) block copolymers become insoluble in water above a certain temperature, usually designated as the cloud point. The polymer chains collapse at this temperature, and, consequently, flocculation of aqueous dispersions or emulsions stabilized by these surfactants occurs when the system is heated above the cloud point. 

Because the nanosizes of reversed micelles as well as water pools change with iVg, the volume of the compartmentalized entity can be easily controlled. Flost molecules are compartmentalized and localized in the reversed micelles by the electrostatic and hydro-phobic interactions. The bound water exists overwhelmingly below JVg = 10 regardless of cationic and anionic surfactants. However, since in the case of nonionic ethylene oxide surfactants, the oxygen atom of ethylene oxide is hydrated with two to four water molecules, the appearance of free water depends on the chain length of ethylene oxide [61-64]. 

The two surfactant polymers used to stabilize the heptane and water emulsion were poly(ethylene oxide), PEO, and poly(vinyl alcohol), PVA. Poly(ethylene oxide), also known as Polyox, was obtained from Union Carbide Corporation, South Charleston, West Viriginia, Polyox WSR N-10, the grade of polymer used in this work, had an average molecular weight of 100,000. The poly(vlnyl alcohol) used was marketed by Monsanto, St. Louis, Missouri, as Gelvatol 20/90. This polymer has an average molecular weight of 125,000. 

The potential of microemulsions for organometaUic-catalyzed hydrogenations in water/scC02 biphasic systems has been assessed using the rhodium-catalyzed hydrogenation of styrene as a common test reaction [Eq. (7)] [31]. The water-soluble Wilkinson complex [RhCl(TPPTS)3] was applied as catalyst precursor together with anionic perfluoropolyether carboxylates, cationic Lodyne A, or nonionic poly-(butene oxide)-b-poly(ethylene oxide) surfactants. The interfacial tension is small in the presence of the supercritical fluid and small amounts of surfactant (0.1-2.0 wt.%) suffice to form stable microemulsions. The droplet diameter of the microemulsions varied between 0.5 and 15 pm and a surface area of up to 10 m was obtained. 

DEL DeLisi, R., Lazzara, G., Milioto, S., and Muratore, N., Thermodynamics of aqueous poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)/surfactant mixtures. Effect of the copolymer molecular weight and the snrfactant alkyl chain length,/. Phys. Chem. B, 108, 18214, 2004. 

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