Polyoxyethylene chain

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... 

Ethoxyl tion. Base-cataly2ed ethoxylation of aUphatic alcohols, alkylphenols, and fatty acids can be broken down into two stages formation of a monoethoxy adduct and addition of ethylene oxide to the monoadduct to form the polyoxyethylene chain. The sequence of reactions is shown in equations 20—22 ... 

The product is a mistuie of various polyoxyethylene chain lengths (29—31). Glycol diesters ate used as vinyl plasticizers the monoesters as surface-active agents and viscosity modifiers for alkyd resins (qv). 

In a study of the adsorption of soap and several synthetic surfactants on a variety of textile fibers, it was found that cotton and nylon adsorbed less surfactant than wool under comparable conditions (59). Among the various surfactants, the cationic types were adsorbed to the greatest extent, whereas nonionic types were adsorbed least. The adsorption of nonionic surfactants decreased with increasing length of the polyoxyethylene chain. When soaps were adsorbed, the fatty acid and the aLkaU behaved more or less independently just as they did when adsorbed on carbon. The adsorption of sodium oleate by cotton has been shown independently to result in the deposition of acid soap (a composition intermediate between the free fatty acid and the sodium salt), if no heavy-metal ions are present in the system (60). In hard water, the adsorbate has large proportions of lime soap. 

Possibility of changing the properties of micellar phases by electrolyte inclusions was shown. Under this condition, in the systems with manifestation of complexes formation between the cationic compound of the electrolyte and the polyoxyethylene chain of the surfactant, increase of the hydrophilic properties of micellar phases was observed. The electrolytes that do not have affinity to the surfactant s molecule practically do not influence the liophily of the nonionic surfactant-rich phases. 

There is even a method for preparing carboxymethylated surfactants with a narrow polyoxyethylene chain distribution by using as catalyst metallic Na or NaH in a molar ratio of about 1 1 to the fatty alcohol [12,13]. 

Isolated unperturbed polyoxyethylene chains have been simulated on the 2nnd lattice [154], The literature contains RIS models for a large number of polyethers [124], and it is likely that most of these chains could be mapped onto the 2nnd lattice with little difficulty. It is also likely that the work on PP [156,158] can be extended to other vinyl polymers, such as poly(vinyl chloride). This capability should permit the construction and complete equilibration of amorphous poly(vinyl chloride) cells larger than those described to date. They may be large enough to address issues arising from the weak crystallization reported for these systems [174]. 

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],... 

Three azobenzeneophane-type crown ethers in which the 4,4 positions of azobenzene are joined by a polyoxyethylene chain have been synthesized (Shinkai, Minami, Kusano Manabe, 1983). On irradiation with UV light, the ( ) (or trans) form (198) is isomerized to the (Z) (or cis) isomer (199). The ( ) isomer may be regenerated by heating, or by irradiation with visible light the interconversion is completely reversible. 

In prior work, related molecules had been obtained in which a polyoxyethylene chain linked the 2,2 -positions of the azobenzene moiety (Shiga,Takagi Ueno, 1980). Howeverforsuchsystems,theds trans interconversion is accompanied by gradual photodegradation probably resulting from the presence of steric strain in the cis isomers. 

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... 

One of the nonionic surfactants most used as an enhancer of chemiluminescent reactions is Brij-35. This surfactant increases the reaction of lucigenin with catecholamines by a factor of 2.6 compared with the CL intensity in an aqueous medium [42], This enhancement can be explained in the following way it is known that oxygen from the polyoxyethylene chains in Brij-35 can react with sodium ion to form an oxonium ion, by which means the polyoxyethylene chains act as an oxonium cation. In this way the increase in CL intensity due to Brij-35 can be attributed to the same effect described for the micelles of a cationic surfactant. 

CYCLISATION OF POLYMETHYLENE AND POLYOXYETHYLENE CHAINS Lactonisatiort of m-bromoalkanoate anions... 

The close adherence of the calculated curve to the actual behaviour of polyoxyethylene chains is further substantiated by comparison with the kinetic EM s for the formation of the 30- and 48-membered benzo-crown ethers [20] in 99% Me2SO (Illuminati et al., 1981 see Fig. 13). Assuming that for... 

One example of the chemical crosslinking strategy is the formation of urethane linkages between polyoxyethylene chains. Fig. 5.17 (Killis et ai, 1982). The urethane crosslinked polyether systems were exploited by Killis et al. in their extensive studies of the relation between conductivity and bulk mechanical properties of network electrolytes. Other chemically... 

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). 

Therefore, the hypothesis of an increasing nonionic character of alkyl ether sulfates with increasing number of oxyethylene groups is not tenable. Some time ago (30), it was suggested that a certain hydrophobic nature can be attributed to the polyoxyethylene chain of alkyl ether sulfates. At first, this appears to be in contradiction to the decidedly hydrophilic character of the polyoxyethylene chain for nonionic surfactants. However, the possibility of EO group hydration impairment by the sulfate group cannot be excluded. 

For compounds with one and two oxyethylene groups in their molecule, the increase of the micelle formation tendency can be explained by a contribution of these groups to the hydrophobic part of the molecule. With a longer polyoxyethylene chain in the molecule, however, the increased tendency to form micelles is primarily caused by the increased distance between the charged groups due to increased hydration of the ether groups. 

Nowadays we look with other eyes at organometallic compounds the family of which has expanded enormously. Some members of this family are soluble in water due to their ionic nature the legions of anionic carbonylmetallates (e.g. [Ni(CN)(CO)3] ) and cationic bisphosphine Rh-chelate complexes (e.g. [Rh(BDPP)(COD)] ) just come to mind. Others obtain their solubility in water from the well soluble ligands they contain these can be ionic (sulfonate, carboxylate, phosphonate, ammonium, phosphonium etc. derivatives) or neutral, such as the ligands with polyoxyethylene chains or with a modified urotropin structure. 

Two types of micellar systems have been described, the first one includes Gd complexes capable of self-organization resulting in a supramolecular assembly 103), while the other class of micelles, also named mixed micelles is made of several components a lipophilic gadolinium chelate, one or several phospholipid(s) and a non-ionic surfactant containing a polyoxyethylene chain 104,105). 

Figure 1 summarizes the significant structural features of four classes of nonionic surfactants discussed in this paper. These are simplified representations of commercial surfactants which contain varying hydrophobe and hydrophile chain lengths. The hydrophiles are represented as polyoxyethylene chains, although such hydrophiles as polyglucosides and polyoxypropylene/polyoxyethylene chains are used to a lesser extent. 

Yellow OB dye is an essentially water—insoluble organic and is convenient to use as a solubi1izate. The studies discussed here use Yellow OB -for solubilization studies in mixed sur-factant systems. Yellow OB can solubilize in the hydrocarbon core o-f the micelle as well as among the polyoxyethylene chains in a micelle with non ionic sur-factant. 

We have discussed the differences in the mixed micelle forming due to the different alkyl chain lengths (ACL) and/or polyoxyethylene chain lengths (PCL) in nonionic surfactants. We found that the mixed micelle would be formed more easily by a nonionic surfactant including long ACL (or shorter PCL) than by one having shorter ACL (or long PCL). We have also reported that the protonation of 4-phenylazo-l-naphthylamine (4-NH2) was caused by... 

Na with the ether oxygens of the polyoxyethylene chain, in a manner similar to their interaction with crown ethers. 

Xla, J. D. Hu, Z. Y. "The Effects of Polyoxyethylene Chain Length Distribution on the Interfacial Properties of Polyoxy-ethylenated n-Dodecyl Alcohols" (in press). 

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