Nonionic surfactants basic properties

Intensive work has been carried out in order to estab lish a relationship between emulsion properties and the properties of surfactant systems. The classical HLB (hydrophile-lipophile balance) concept is widely used in emulsion science to describe the balance of the hydrophilic and lipophilic properties of a surfae tant at oil/water interfaees. The HLB value deter mines flie emulsion inversion point (EIP) at which an emulsion ehanges from W/O to 0/W type. This was of particular importance for nonionic surfactants that change their properties with ehanges in tempera ture (59). Various NMR techniques have provided significant contributions to this basic understanding of surfactant systems and some of those were reviewed in Ref. 7. The usefulness of NMR techni ques in studying surfactant solutions lies in the direct information they provide about the microstracture ofmicroheterogeneous systems (8,60— 64). It is beyond the scope of this chapter to summarize the use of NMR techniques in the study of surfactant systems, but we will present some representative examples related to emulsions. 

The production and properties of alkoxylated nonionic surfactants have been reviewed exten-sively. They are produced by the reaction of hydrophobic feedstocks containing hydroxyl or amine groups with alkylene oxides under pressures of 30-90 psia and at temperatures of 100-140°C in the presence of catalytic quantities of basic or transition metal elements. The degree and type of alkylene oxide appended and the blocking or random copolymerization that is allowed to occur drastically affects the physical and performance properties of the resulting nonionic surfactant. 

MEKC is usually used as a separation technique in which the basic properties of micellar liquid chromatography and CE are combined. MEKC was first described by Terabe in 1984 for the separation of nonionic aromatic compounds and is a powerful separation technique for lipophilic and nonionic species. By addition of surfactants to the background electrolyte, new options for solving electrophoretic separation problems are opened, but it is also possible to apply this technique to study the affinities of drug molecules to surface-active compounds. The term micellar affinity capillary electrophoresis (MACE) is used... 

Alkanoylglycamine surfactants are interesting materials having distinctive properties. Their phase behavior suggests that they are more hydrophilic than typical polyoxyethylene surfaetants, but less hydrophilic than other subclasses of nonionic surfactants (semipolar, zwitterionic). They are far less hydrophilic than ionic surfactants. The eompounds are weakly basic—the pKa of protonated dialkyl amides is about 1—so they remain unprotonated and nonionic within the usual pH range. As a result, they do not display the numerous complexities typieally found in ionic compounds. 

The solubilization of comparably small amounts of oil components in rinse and shampoo formulations demonstrates the basic emulsification properties which alkyl polyglycosides should be expected to show as nonionic surfactants. However, a proper understanding of phase behavior in multicomponent systems is necessary in order to evaluate alkyl polyglycosides as powerful emulsifiers in combination with suitable hydrophobic coemulsifiers [42]. 

When scouring synthetic fibres that are to be dyed with disperse dyes, nonionic scouring agents are best avoided unless they are formulated to have a high cloud point and are known not to adversely affect the dispersion properties of the dyes. Conversely, when scouring acrylic fibres, anionic surfactants should be avoided [156] because they are liable to interfere with the subsequent application of basic dyes. These fibres are usually scoured with an ethoxylated alcohol, either alone or with a mild alkali such as sodium carbonate or a phosphate. 

These can be produced in the form of liquids, creams, gels, powders, granules (beads). Their main function is to produce maximum foam into running water. The basic surfactants used in bubble bath formulations eire anionic, nonionic or amphoteric together with some foam stabilizers, fragrants and suitable solubilizers. These formulations should be compatible with soap cUid they may contain other ingredients for enhancing skin care properties. 

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