Nonionic surfactants ethylene oxide adducts

Nonionic surfactants contain (Fig. 23) no ionic functionalities, as their name implies, and include ethylene oxide adducts (EOA) of alkylphenols and fatty alcohols. Production of detergent chain-length fatty alcohols from both natural and petrochemical precursors has now increased with the usage of alkylphenol ethoxylates (APEO) for some applications. This is environmentally less acceptable because of the slower rate of biodegradation and concern regarding the toxicity of phenolic residues [342]. 

Nonionic surfactants can be mixed as well, but in practice most of them, at least the ethoxylated ones, are already a mixture because of the polycondensation mechanism in ethylene oxide adduction. Isomerically pure ethoxylates are extremely expensive and are exclusively reserved for research work. Little work has been carried out with mixture of isomerically pure nonionics and the bulk of the work on mixture deals with mixtures of commercial products, i.e., mixture of mixtures, which obey a linear mixing rule on EON, provided that the base mixtures are not too different [8,35]. 

More important for the application of nonionics in practice is knowledge of the relationship between the stabilising effect and the average ethylene oxide number in the molecule. The surfactant concentration c, necessary to increase the shelf-life of a standard emulsion is taken as a measure of the stabilising effect. Fig. 1.16 shows such a relationship for ethoxylated dodecanol (Muller Kretzschmar 1982). The ratio of the hydrophilic and hydrophobic parts in the molecule has a direct bearing on the concentration needed to stabilise the toluene-in-water system. The ethylene oxide adducts possesses particularly high variability and are readily available. 

Synonyms Ethylene oxide adduct of 2,4,7,9-tetramethyl-5-decyn-4,7-diol Tetramethyl decynediol ethoxylate 2,4,7,9-Tetramethyl-5-decyne-4,7-diol ethoxylate Classification Nonionic surfactants Formula ... 

The typical MS spectrum of polyethoxylates yields a characteristic pattern of equally spaced signals with mass differences of 44 Da (one ethylene oxide unit), which is a diagnostic fingerprint for this group of compounds. The nonionic surfactants easily form adducts with alkaline and other impurities. Using an ESI interface and aprotic solvent APEOs predominantly give evenly spaced sodium adducts [M-t-Na] due to the ubiquity of sodium in the solvents and surfaces. Sodium adducts are relatively... 

Wickbold, R., Chromatographic separation of ethylene oxide adducts into their homologs, and their quantitative determination (in German), Fette, Seifen, Anstrichm., 1968, 70,688-692. Leon-Gonzalez, M. E., M. J. Santos-Delgado, L. M. Polo-Diez, Triton-type nonionic surfactants by on-line clean-up and flow injection with spectrophotometric detection. Analyst, 1990, //5, 609-612. 

Although there are other types of nonionic surfactant, the great majority are adducts of ethylene oxide with hydrophobes derived from three sources ... 

---