Methyl ester ethoxylates performance

Cox, M. F., Weerasooriya, U. 1998. Impact of molecular structure on the performance of methyl ester ethoxylates. J. Surfact. Deterg. 1 11-22. 

Methyl ester ethoxylates are similar in structure to conventional alchol ethoxylates, but the structural differences that do exist have an important impact on their performance. As shown in Fig. 1, methyl ester ethoxylates contain an ester linkage at the hydrophobe-hydrophile boundary of the molecule in place of the ether linkage in alcohol ethoxylates. This ester linkage sterically constrains the molecule, which reduces the tendency of the surfactant to micellize and leads to a higher critical micelle coneentration... 

Another feature that dilferentiates methyl ester ethoxylates from alcohol ethoxylates in unsaturatinon. Methyl esters, particularly those in the tallow range, are relatively highly unsaturated, generally more than 50%. Alcohols, in contrast, are typically fully saturated. The impact of unsaturation on performance can be significantly, and is addressed in the last section of this chapter. 

The impact of molecular structure on the ability of methyl ester ethoxylates to lower interfacial tension has been examined elsewhere [14]. These studies show that the relative performance of methyl ester and alcohol ethoxylates and the impact of ethylene oxide content and distribution depend strongly on the composition of the soil used to determine the in-terfadal tension. 

Based on the surface property data discussed earlier, methyl ester ethoxylates would be expected to perform similarly to alcohol ethoxylates, which is indeed the case. As shown in Fig. 13, methyl ester ethoxylates are comparable to alcohol ethoxylates, as well as other commonly used surfactants (see Table 1), in their ability to remove soil from fabric. Compositional variables affect the performance of methyl ester ethoxylates and alcohol ethoxylates. Lauryl range and tallow range methyl ester ethoxylates provide the best detergency, while optimal ethylene oxide content appears to depend on soil/ cloth-type (Fig. 14). Interaction with other surfactants also affects detergency performance. As shown in Fig. 15, methyl ester ethoxylates act synergistically with alcohol ethoxylates, while the opposite can be observed with alcohol sulfate and alcohol ether sulfate. 

FIG. 13 Fabric detergency performance of methyl ester ethoxylate vs. conventional surfactants. (Conditions, test method, and protocol described elsewhere [15], descriptions of reference surfactants are given in Table 1 distribution for C -is methyl ester = 57% C12, 23% C14, 12% Cig, and 8% Cig MEEs prepared using calcium/aluminum alkoxide catalyst. (From Ref. 27.)... 

FIG. 14 Fabric detergency performance of methyl ester ethoxylates as a function of carbon chain length and EO content. (From Ref. 15.)... 

Based on the surface property data discussed earlier, methyl ester ethoxylates would be expected to perform similarly to alcohol ethoxylates, which is indeed the case. As shown in Figure 13, methyl ester ethoxylates are comparable to al-... 

Ethoxylated acids can be differentiated from AE and APE (other than by spectroscopy) because the former are esters and thus are hydrolyzed in the presence of acid or (more often) base to form the starting acid and PEG. This operation may be performed in methanol to directly give methyl esters of the fatty acids for further analysis. 

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