Hydrophilic polyoxyethylene

In this schematic, the /3-lg molecules are depicted as jigsaw puzzle pieces, since the protein-protein interactions in the interface generated by this particular protein are very strong [3]. The experimental evidence is consistent with the complex formed between /3-lg and Tween 20 being unable to interact with /3-lg or other molecules of the complex. It is convenient to depict the complex in our schematic model by shielding the protein-protein interaction site on the icon with the hydrophilic polyoxyethylene chain of the Tween 20 molecule. This is... 

Poloxamers are neutral block copolymers such as 12, consisting of two terminal hydrophilic polyoxyethylene blocks flanking a central hydrophobic polyoxypropylene block. Poloxamer 188 (e.g., Pluronic F-68) was used in the first generation PFC emulsions, but was far from adequate Its surface activity is relatively poor, translating into low emulsions stability the purity of the commercial products is usually rather low its cloud point ( 110-115°C) prevents sterilization at the standard temperature of 121°C its tendency to form gels limits the PFC concentration in the emulsions and, finally, Pluronic F-68 has been found to be responsible for the unpredictable transientcomplement activation-mediated anaphylactic reaction observed in some patients in response to the injection of Fluosol. ... 

Analysis of these has allowed, 2, K i and X2 to be estimated and related to the nature of the binding process in the micelles, especially in respect of the interaction with the hydrophilic polyoxyethylene layer [32]. 

Adsorption of t-PA to process equipment surfaces consisting of either stainless steel or glass was minimized by adding the detergent polyoxyethylene sorbitan monooleate (Tween 80) to the semm-free culture conditioned media at 0.01% (vol/vol). The equipment was also rinsed, before use, with phosphate buffered saline (PBS) containing 0.01% Tween 80. Hydrophilic, plastic equipment was used whenever possible. AH buffers were sterile filtered. Sterile filtration of Hquids and gases is usually carried out using 0.2 or 0.45 p.m filters. 

Ethoxylated Anhydrosorbitol Esters. Ethoxylation of sorbitan fatty acid esters leads to a series of more hydrophilic surfactants (Table 19). All hydroxyl groups of sorbitan can react with ethylene oxide. The stmcture of the principal component of a nominal polyoxyethylene (20) sorbitan monostearate illustrates the composition of these products, where w x y z = 20. 

Natural Ethoxylated Fats, Oils, and Waxes. Castor oil (qv) is a triglyceride high in ticinoleic esters. Ethoxylation in the presence of an alkaline catalyst to a polyoxyethylene content of 60—70 wt % yields water-soluble surfactants (Table 20). Because alkaline catalysts also effect transestenfication, ethoxylated castor oil surfactants are complex mixtures with components resulting from transesterrfication and subsequent ethoxylation at the available hydroxyl groups. The ethoxylates are pale amber Hquids of specific gravity just above 1.0 at room temperature. They are hydrophilic emulsifiers, dispersants, lubricants, and solubilizers used as textile additives and finishing agents, as well as in paper (qv) and leather (qv) manufacture. 

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). 

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. 

Reactions between oligomers to-hydroxypolyoxyethylene and experimental data with the established kinetic law230. This is presumably due to the hydrophilicity of polyoxyethylene which retains the reaction water and therefore favours the hydrolysis of the catalyst. Consequently, it is not surprising that only low values of rate constants were obtained. The best fit was found for an overall reaction order close to 2.5. 

Argillaceous formations are very reactive in the presence of water. Such formations can be stabilized by bringing them in contact with a polymer solution with hydrophilic and hydrophobic links [101-104]. The hydrophilic portion consists of polyoxyethylene, with hydrophobic end groups based on isocyanates. The polymer is capable of inhibiting the swelling or dispersion of the argillaceous rock resulting from its adsorptive and hydrophobic capacities. 

Dewatering surfactants can be polyoxyethylene, polyoxypropylene, and polyethylene carbonates [1348] or p-tert-amylphenol condensed with formaldehyde, or they can be composed of a copolymer from 80% to 100% alkyl methacrylate monomers and hydrophilic monomers [777]. Such a well treatment fluid may be used in both fracturing and competition operations to enhance and maintain fracture conductivity over an extended period of production. 

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. 

This paper is largely confined to the alkyl and aryl polyoxyethylene ethers, as these form series variable in both hydrophobic and hydrophilic chain length, and hence HLB, with minimal structural variation. 

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. 

For an ionic/nonionic system, where the nonionic is a polyethoxylate, the greater the degree oF polymerization oF the polyoxyethylene hydrophilic group, the greater the deviation From ideality. 

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