Degree of ethoxylation

Steinle et al. [426] studied the primary biodegradation of different surfactants containing ethylene oxide, such as sulfates of linear primary alcohols, primary oxoalcohols, secondary alcohols, and primary and secondary alkyl-phenols, as well as sulfates of all these alcohols and alkylphenols with different degrees of ethoxylation. Their results confirm that primary linear alcohol sulfates are slightly more readily biodegradable than primary oxoalcohol sulfates and that secondary alcohol sulfates are also somewhat worse than the corresponding linear primary. 

Alkylphenol ether sulfates are slightly more resistant to biodegradation than alkylbenzenesulfonates. Similarly to alcohol ether sulfates, this resistance increases with the degree of ethoxylation. Again there are some differences in favor of primary alkylphenol ether sulfates with respect to secondary alkylphenol ether sulfates [426]. 

Generally ether carboxylates are not suitable for a syndet soap because they are waxy due to the ethylene oxide distribution. The solid ether carboxylates with a long alkyl chain and a low degree of ethoxylation have a bad foam. By use of nonethoxylated ether carboxylates, e.g., a carboxymethylated fatty acid monoethanolamide with the structure... 

The surface-active properties of ether carboxylates have been compared with soaps as well as with those of nonionic and anionic surfactants in addition, the influence of fatty chain and degree of ethoxylation has been investigated. 

Highly concentrated ether carboxylic acids with a low degree of ethoxylation even at room temperature can give an esterification reaction with the non-converted nonionic, especially with the fatty alcohol, to several percentage points. The result may be that a too low value is found for the ether carboxylate content. This mistake in analysis can be avoided by saponification of the formed ester [238]. Two hundred to 300 mg matter and ca 100 mg NaOH were weighed in a 50-ml Erlenmeyer glass, heated with 20 ml ethanol under reflux, and after cooling supplied with water to 100 ml. Afterward a two-phase titration was carried out. 

In the sulfosuccinate esters a comparable hydrophobic part consists of the fatty chain plus the functionalities introduced by maleic acid anhydride function. The product variation would then be possible by changing the chain length and/or degree of saturation of the fatty alcohol. The fatty alcohol itself can be replaced by an ethoxylated fatty alcohol with different degrees of ethoxylation as another parameter to be varied. 

Fatty alcohol + ethylene oxide Chain length Degree of saturation Purity Degree of ethoxylation Distribution of homologs... 

A lauryl alcohol ethoxylate therefore will not only contain ethoxylated alcohol with a degree of ethoxylation from 1 to 10 mol of ethylene oxide according to a Poisson contribution but due to currently typical production methods also significant amounts of unreacted fatty alcohol. 

Comparative primary skin irritation scores of surfactant solutions (15% active content) show various types of sulfosuccinates as being the least irritant materials, well below sodium laureth-3 sulfate. It was also shown that an increase in degree of ethoxylation reduces skin and eye irritation, leading to laureth-3 (lauryl alcohol with 3 mol ethylene oxide) as the ideal organic raw material [17]. The results are given in Fig. 9 for eye irritation and in Fig. 10 for skin irritation. 

Acid ester phosphates with an alkyl chain up to C6 have little solubility whereas neutralized esters are soluble in water. In ethanol and isopropanol most of phosphoric acid esters and their salts are soluble. If the products are based on ethoxylated alcohols their solubility in water will increase as the degree of ethoxylation increases. The solubility in organic solvents like gasoline, benzene, perchlorethylene, and other apolar liquids recedes with an increase in the degree of ethoxylation but are increased by a higher alkyl chain. 

FIGURE 25 Reduction in the rate of hydrolytic chain scission of PCL achieved by ethoxylation of the carboxy end groups of the polymer. The experimental result is compared with calculated predictions of the effect of varying degrees of ethoxylation. (From RGf. 49.)... 

Taking in account the results obtained by Graciaa (8) and Osborne-Lee (9) for alkylbenzene sulfonate and alkylphenols with an increasing degree of ethoxylation, we have considered that the interaction between sulfonate and associated highly ethoxylated nonylphenol (with 30, 50 or 100 E.O.) was predominant in mixed micelles of the mixtures investigated. 

Comparison of Retention Properties of Three Desorbents with an Increasing Degree of Ethoxylation The individual behavior of three nonionic desorbents (NP 14, 30 and 100 E.O) is compared in Figure 8. Slug size was 1.16 PV in those tests. The outflow of the tracer indicates the slug front of the additive injected. The concentration used was 5 g/1 in all tests. On a weighted basis, it was the NP 30 E.O., that led to the lowest final retention, i.e. 0.30 mg/g of rock (Table II). 

The adverse effect of nonionic adducts of low cloud point can be avoided by the use of hybrid agents of the ethoxylated anionic type, variously and confusingly referred to as modified nonionic , modified anionic or weakly anionic types. Thus Mortimer [113] has proposed the use of products of the ethoxylated phosphate type (12.27). In this structure, R, as well as the degree of ethoxylation (n) may be varied to optimise the overall HLB value. The numerous ether groups are said to enhance the dye-solubilising and levelling capacity, whilst the polyphosphate grouping exerts several useful effects [113]. These compounds ... 

Commercial AESs are produced via sulfation of AEs, which are also directly used as non-ionic surfactants (see below). AES preparations typically also contain some level of alkyl sulfates. The majority of technical AES blends are obtained from AE feed stocks that have alkyl chains in the range of 12-15 and an average degree of ethoxylation of three. 

Fig. 2.2.5. Migration behaviour of octylphenol ethoxylates with dependence on degree of ethoxylation. Buffer 10 mmol LT1 phosphate, pH 6.8, 70 mmol L-1 SDS, 35% acetonitrile. Samples Igepal CA-520 (n — 5) Triton X-100 (n — 9-10) Igepal CA-720 (n — 12) Triton X-405 (n = 40). Reprinted with permission from Ref. [22] 1997 Springer Verlag.

Degree of ethoxylation, 8ethox Increases with increasing 8ethox... 

Commercial nonionic surfactants are mixtures of multiple species with different degrees of ethoxylation and typically with some distribution in hy-... 

As a practical example for the phase behaviour of surfactants, Figure 3.18 shows the phase diagram of a pure non-ionic surfactant of the alkyl polyglycol ether type C Em. n denotes the length of the hydrocarbon chain and m the degree of ethoxylation [20]. 

This class of surfactants has possibly the widest range of use of any anionic surfactant. It is found in almost every product where foaming is desirable, in industrial, household and personal care applications. Alkyl ether sulphates are described in terms of their parent alcohol and the degree of ethoxylation. Thus, sodium laureth-2 is the sodium salt of a sulphated (predominantly) C12 alcohol, with an average of 2 mol of ethylene oxide added. Often, the alcohol is assumed to be the typical C12-14 and the surfactant simply called a 2-or 3-mol ether sulphate. 

Chemistry and general properties. The chemistry of ether sulphates is very similar to that of alkyl sulphates. The backbone of the molecule is a fatty alcohol and often the same alcohols are used as feedstocks for alkyl sulphates, and alkyl ether sulphates and, with higher degrees of ethoxylation, as non-ionic surfactants. The ethoxylation process is more fully described in Chapter 5. 

Ether sulphates show a strong salt effect - that is an increase in viscosity on addition of salt (or other electrolyte). The response to electrolyte (the salt curve ) can be very different between ether sulphates, even from different suppliers of the same product. Generally, the more soluble the surfactant, the lower the salt response but higher degrees of ethoxylation reduce salt response, as does branching in the alcohol as shown in Figure 4.20. 

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