Nonionic surfactants oxyethylated surfactant

At first aqueous solutions of a nonionic surfactant, oxyethylated isononyl-phenol (EOio) with molecular mass M = 666 and critical micelle concentration (CMC) = 0.01%, were used [8]. The experiments were performed at solution concentration Cq = 0.025%, much higher than CMC. The solution was prepared using triply distilled water with electrical conductivity of 10 cm and pH 6.5. Surface tension of bulk solution equals 7 = 31mN/mat t = 20°C. 

In the solutions of both the anionic SDS surfactant (Figure 2.13) and the cationic CTAB surfactant (Figure 2.14), the systems are in equilibrium and display full reversibility. To some extent, this is also true for a nonionic surfactant, oxyethylated ether (Figure 2.15), but in this case, equilibrium is not reached instantaneously, as the value of Pi shows strong time dependence (Figure 2.16). In the... 

With the exception of fluorinated surfactant III, the fluorinated surfactants tested are less toxic to algae than to fish. Fluorinated surfactant I is less toxic to algae and to fish than the coiTesponding hydrocarbon-type nonionic surfactants (oxyethylated /i-tetradecanol, with 10-15 EO (ethylene oxide) units). The noeffect concentrations and the IC50 values for fluorinated surfactant II and for its nonfluorinated counterpart (sodium pentadecanesulfonate) are about the same, but the LC50 value for the hydrocarbon-type surfactant is about 10 times lower. 

Surfactants. The use of surfactants is greatly restricted in formulating ophthalmic solutions. The order of surfactant toxicity is anionic > cationic >> nonionic. Several nonionic surfactants are used in relatively low concentrations to aid in dispersing steroids in suspensions and to achieve or to improve solution clarity. Those principally used are the sorbitan ether esters of oleic acid (Polysorbate or Tween 20 and 80), polymers of oxyethylated octyl phenol (Tyloxapol), and polyoxyl 40 stearate. The lowest concentration possible is used to perform the desired function. Their effect on preservative efficacy and their possible binding by macromolecules must be taken into account, as well as their effect on ocular irritation. The use of surfactants as cosolvents for an ophthalmic solution of chloramphenicol has been described [271]. This com-... 

The dependence of equilibrium film thickness on surfactant concentration has been studied for various surfactant kinds ionic surfactants dodecyl- and tetradecyl sodium sulphate, Igepon T, cetylpyridine chloride, cetyltrimethylammonium bromide [95,189] nonionic surfactants 15- and 20-oxyethylated octylphenols, 6- and 11-oxyethylated dodecyl alcohols, dimethylsulphoxide [189]. Fig. 3.20 depicts the h(C) dependence for some of these surfactants. 

Oxyethylated surfactants The multiple condensation of ethylene oxide with a hydrophobe that contains accessible hydrogen atoms yields a polyethylene-oxide with an attached hydrophobic tail group. Polyethyleneoxide surfactants constitute the major portion of nonionic surfactants. The ability to control the... 

It should be noted first that the Frumkin model is the most general one with respect to its application to surfactants of different nature. In spite of the fact that, e.g., for oxyethylated nonionic or ionic surfactants this model is essentially biased, in the majority of practical cases it can be recommended irrespectively of the nature of the surfactant. In the Frumkin model, three parameters are necessary to describe the adsorption and surface tension isotherm. Leaving aside the molar area co which can be estimated from the molecular geometry [16, 84], we concentrate on the results which follow from our development for the parameters a and b for surfactant molecules with linear hydrocarbon chain. Figure 3.59 illustrates the dependence of the Frumkin constant a on the molar area co of various surfactants at n<- = 10. Note that for ionic surfactants the co values are equal to the doubled values of co, from corresponding tables. 

Up to early 1990s, it was assumed that oxyethylation can occur only when the hydrophobic reagent had a labile hydrogen [1-3,5]. Thus, fatty acid methyl esters (FAME) were not considered as a raw material for the direct synthesis of nonionic surfactants with a polyoxyethylene chain. However, esters of fatty acids and PEG monomethyl ethers were known and their properties were described [6]. They were synthesized in a two-step process. Methanol was oxyethylated to PEG monomethyl ether that was then converted into the final product by transesterification with FAME or by esterification with fatty acids, carried out in the presence of an alkaline B or an acid catalyst, respectively. Esters of typical nonionics were synthesized in similar ways and their properties were described [7-9]. 

Oxyethylated FAME exhibits the surface-active and nsage properties similar to typical nonionic surfactants, including oxyethylated alcohols [25,49-64]. It is obvious that there are some differences, connected with the somewhat different structure, that is, the presence of a terminal methyl group. As a result, oxyethylated FAME show lower foaming ability, lower clouding points, and different tendency for gelation. 

Concentration and separation of dyes in nonionic surfactant anploying a cloud point technique has been explored by Tatara et al. (2(X)4). The researchers used oxyethylated nonionic surfactants and investigated their potential to separate two direct dyes and one basic dye for recovery. It was found that the method had some potential however, separation occurred slowly by accumulation of the organic solute in the surfactant-rich phase. Both surfactant and dye as well as other reaction parameters had to be selected appropriately for reasonable results. Cloud point extraction was also explored by Purkait et al. (2(X)4) for the direct dye Congo Red. Nonionic surfactant was used and recovered from the dilute phase by solvent extraction with heptane. 

The contact of a lubricating substance with a solid is particularly significant from a tribological point of view. Oxyethylated alcohols are nonionic surfactants, and their interactions with the surface are basically quite specific (hydrogen bonds). The contribution of universal (electrostatic) interactions is considerably smaller, as these are very weak dispersion interactions. In the solution in contact with a solid, one can distinguish the surface phase and the bulk phase. Due to adsorption from solutions, the surface phase is enriched with the component that has a stronger affinity for the surface. It is a characteristic of adsorption from solutions on a solid surface that individual components compete for free sites on the surface. At this point, one should not confuse adsorption with absorption, the latter of which may lead to penetration of the components into the solid. 

FIGURE 4.23 The equilibrium values of the free energy of interaction between two methylated glass spheres as a function of a nonionic surfactant concentration (c, 10 " mol/L). The nonionic surfactant is oxyethylated ether, Ci E q. 

The base-catalyzed reaction of the oligomers with oxyethylated alcohols gives ethers which can also be converted to nonionic surfactants ... 

Unlike the phenyl ethers, the alkyl ethers thus formed react readily with nucleophilic reagents. The reaction with another oxyethylated alcohol molecule gives a nonionic surfactant with two oxyethylene chains,... 

The method selected for the preparation of a nonionic fluorinated surfactant depends on the hydrophile, which can be either an polyalkyl ether chain or a polyhydroxy group. Because oxyethylation results in a mixture of oligomers, special methods have been devised for the preparation of monodisperse surfactants. A unique group of nonionic surfactants are amphiphiles without a hydrophile. Semi-fluorinated alkanes with an oleophilic and an oleophobic segment function as nonionic surfactants in oleophilic solvents (see Section 1.8). 

Telomer perfluoroalkylmethanols have been oxyethylated to form nonionic surfactants having the structure RfCH20(CH2CH20) H [222,223]. 

Nonionic surfactants can be prepared by a reaction of the tetrafluoroethylene pentamer with alcohols or with a phenol [96,97]. The reaction product obtained with phenol is sulfonated to produce a sulfonyl chloride. A reaction of the sulfonyl chloride with with iV-ethylethanolamine yields an alcohol, which is oxyethylated to produce a nonionic surfactant ... 

A fluorinated thiol is reacted with monochlorohydrin and the resulting alcohol is oxyethylated to yield a nonionic surfactant [238]. Perfluoroalkylmercap-tan, RfCH2CH2SH, epichlorohydrin, and Carbowax 350 were reacted to prepare the surfactant RfCH2CH2SCH2CH(OH)CH20(CH2CH20)7CH3 [239]. 

Polymerizable nonionic surfactants can be obtained by reacting the poly-oxyethylated oxirane with A. A -diallylamine, acrylic acid, or methacrylic acid as the nucleophile [250]. 

Plurafac [BASF], TM for a series of 100% active, nonionic biodegradable surfactants of straight-chain, primary aliphatic oxyethylated alcohols. Available in liquid, paste, flake, and solid form. 

The PIT appears to reach a constant value at 3-5% surfactant concentration when a POE nonionic containing a single POE chain length is used. When there is a distribution of POE chain lengths in the surfactant, the PIT decreases very sharply with increase in the concentration of the surfactant when the degree of oxyethyl-enation is low and less sharply when the degree of oxyethylenation is high. 

As shown in Figure 18.5, l//,l//-perfluoroalkanols are an important group of intermediates that can be obtained from PFCA fluorides obtained by electrochemical fluorination (or, alternatively, by a telomerization process ). These alcohols are readily converted into polydisperse nonionic polyoxyethylene surfactants by reaction with oxirane (or analogues) in the presence of a catalyst (Scheme 18.13). Borontrifluoride etherate is the classical catalyst for this oxyethylation reaction, but there are claims for the utilization of other catalysts such as aluminum alkoxides, sodium hydroxide, and acidic catalysts. ... 

Examples of nonionic fluorinated surfactants are given in Table 1.7. Typical nonionic fluorinated surfactants are oxyethylated alcohols, amines, or thiols (mercaptans). 

The preparation of nonionic fluorinated surfactants from fluorinated alcohols is straightforward [218-230]. Perfluoroalkylethanol (see Section 2.3), obtained from telomer perfluoroalkylethyl iodides, is oxyethylated in the presence of a catalyst, for example, BF3 ... 

Nonionic fluorinated surfactants are prepared from acid fluorides, obtained by electrochemical fluorination, usually with an amide as the intermediate. Sul-fonyl fluorides are converted with an amine to the amide, which is reacted with ethylene chlorohydrin and oxyethylated ... 

Perfluoroalkanoic acids can be converted to nonionic fluorinated surfactants by a reaction with oxyethylated propylenediamine [93] ... 

The biodegradation of FC-171, a nonionic fluorinated surfactant, was measured by the modified ISO Standard Aerobic Shake Flask Test [21a]. The test uses nutrient salt in a brine (seawater) solution in which the fluorinated surfactant is the only organic solute. No significant biodegradation was observed after 9 days, but after 57 days, dissolved organic carbon (DOC) was reduced from 14.5 to 6.0 mg/L. Because the perfluoro chain was probably not degraded, the results indicate a 90% degradation of the oxyethylated part of the surfactant molecule. 

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