Ethylene oxide, chain length

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

FIGURE 18.2 Capillary gel electrophoresis separation of an octylphenol ethoxylate sulfate (with an ethylene oxide chain length from 1 to 8). Run conditions pH 8.3 (100 mM tris-borate, 7 M urea) 50 pm x 75 cm J W polyacrylamide gel capillary (PAGE-5, 5%T, and 5%C) run at 20 kV with a 5kV injection for 5 s UV detection at 260nm. 

The promotion of insulin absorption from the rectal cavity has been studied by Touitou et a, (9 ), Figure 3 illustrates the marked influence of ethylene oxide chain length in the Ci2 series and of alkyl chain length in the CxEg series. This striking demonstration of the structural dependence of activity is indicated with the loss of activity when the Ci2E25 C12E4Q compounds are used. Here appears to be the most active... 

In all of these data what requires explanation is the effectiveness of the dodecyl chain, the decreasing activity with increasing ethylene oxide chain length above EiQ-14 the increase in activity when we move from a very hydrophobic surfactant with short ethylene oxide chain to the optimum, and the decrease in activity with increasing lipophilicity of compounds with alkyl chain lengths greater than Cl2. 

A parabolic relationship between membrane activity and lipophil-icity of nonionic surfactants is clearly established in series of surfactants in which either the hydrocarbon chain length or ethylene oxide chain length is varied. Activity at low and high concentrations should be considered separately. 

Figure 2. CMC s for 3((>Cxo/Nl E50 mixtures variation of the mixture critical micelle concentration with monomer phase composition for mixtures of decyl benzene sulfonate with a nonyl phenol ethyoxy-late having an ethylene oxide chain length of 50, at 27 °C.

Abbreviated C)2E6 to denote hydrocarbon and ethylene oxide chain lengths. 

Foy and Smith (4) recently reviewed the role of surfactants in modifying the activity of herbicidal sprays (66 references). These authors studied the adjuvant effects of a surfactant based on nonyl phenol with varying amounts of ethylene oxide appended. Activity was enhanced at an optimum ethylene oxide chain length. This is another way of stating that there is an optimum surfactant HLB for enhancing herbicidal activity on a given species of weed. 

Surfactant foaming properties are related to surfactant chemical structure parameters such as hydrophobe size, ethylene oxide chain length, and hydrophile functional group. 

The low correlation coefficient observed when combining the data for alcohol ethoxylates from two different manufacturers is probably due to chemical structure variables not incorporated in equation 1. These include different degrees of hydrophobe linearity, different distributions of carbon numbers and ethylene oxide chain lengths around the average values used in the correlation equation, and the presence of differing amounts of other components such as unreacted alcohols in the surfactants. 

Foaming properties of alcohol ethoxylates and alcohol ethoxylate derivatives are related to chemical structure features such as hydrophobe size and linearity, ethylene oxide chain length, and the terminating group at the end of the ethylene oxide chain. Foaming properties may be mathematically related to chemical structure parameters using multiple correlation analysis. ... 

When studying commercial surfactants obtained from different suppliers and possibly manufactured by different synthetic routes, variations in hydrophobe carbon number distribution, hydrophobe chain branching, the distribution of ethylene oxide chain lengths about the average value, and the nature and concentration of impurities has to be considered. 

Figure 6.4 Surface tension versus log concentration plots for nonionic surfactants with the general formula CH3(CH2),5 (0CH2CH2) 0H for o series of ethylene oxide chain lengths, n.

The effect of an increase in the ethylene oxide chain length of a polyoxyethylated nonionic... 

To avoid agglomeration, one possibility is to use a saturated fatty acid instead of oleic acid. Also, the use of such surface-active agents that are both oxidation inhibitors and form micelles only at concentrations larger than the ones used is recommended. Examples of such surfactants are the polyoxyethylene fatty amines. Since the critical concentration for micelle formation increases with decreasing alkyl- and increasing ethylene oxide chain length, short alkyl and long polyoxyethylene chains are favorable, such as Ethomeen C-25. 

Maruyama, K., Yuan, M., and Otsuki, A., Seasonal changes in ethylene oxide chain length of poly(oxyethylene)alkylphenyl ether non-ionic surfactants in three main rivers in Tokyo, Environ. Set Technol, 34, 343-348, 2000. 

Along with the desired main product, industrial ethoxylated alcohols contain some quantity of initial alcohol as impurity, especially at low m, and free PEG the amount of which increases with m. Ethoxylated alcohols represent mixtures of oligomer-homologues with a wide ethylene oxide chain length distribution. Hence m is always some average value. 

Figure 1 Polymorphism of surfactant self-assemblies, here illustrated in terms of the effect of temperature and ethylene oxide chain length for nonionic surfactants. (Not all possible structures are shown.)...

Figure 11 Cloud-point temperature of micellar solutions as a function of the ethylene oxide chain length the hydrophobic part is an alkyl chain with 8 ( ), 10 ( ), 12 ( ), or 16 ( ) carbon atoms. Data from Ref. 51. The sjunbols ( ) represent the phase-inversion temperature for a 1 1 cyclohex-ane-water emulsion containing 5% of commercial ethylene oxide based emulsifiers having dodecylalkyl chains as a hydrophobic group. (Data from Ref. 54.)...

Since there are many different types of nonionic detergents and the individual types may also have different ethylene oxide chain lengths, reference must be established to a standard substance with a known molecular weight this is, of course, not necessary if it is known which nonionic surfactant is present in the water sample. 

Primary alcohol ethoxylates are an important class of detergent feedstock for anionic active manufacture. They are made by the addition of ethylene oxide to a primary alcohol in the presence of an alkaline catalyst. The addition of the second ethylene oxide molecule to the alcohol is kinetically favoured in comparison with the addition of the first ethylene oxide, hence the product of ethoxylation contains a distribution of ethylene oxide chain lengths attached to the alcohol along with the starting alcohol itself. Consequently the physical, detergency and biodegradation characteristics are affected not only by the carbon chain length distribution as is the case for primary alcohols, but also by the ethylene oxide distribution which in turn can be supplier dependent. 

Hydrocarbon and ethylene oxide chain-length distributions are determined by gas or liquid chromatography. 

---