Polyhydroxy surfactants

Polyhydroxy surfactants have recently received some attention as alternatives to EO materials. Polyhydroxy compounds are more strongly hydrated than EO groups hence the mesophases exist to high temperatures. Also, the intermolecular H-bonding... 

Polyhydroxy surfactants have recently received some attention as alternatives to EO materials. Polyhydroxy... 

The use of alkyl ether carboxylates in manual dishwashing agents was described in 1966 [136]. Subsequently several patents mention combinations of alkyl ether carboxylates with aminoxides [137,142], betaines [138,139,142], different anionic surfactants [140], quaternary compounds [141], alkylpolyglucoside [142], and polyhydroxy fatty acid amide [143]. In all cases the ether carboxylates are used to improve mildness and to achieve good cleaning and lathering properties. 

Surfactants in broad use may be classified into three general types (I) anionics, in which the hydrophilic portion of the molecule carries a negative charge (2) cationics. in which the charge of this portion is positive and (3) nonionics, which do not dissociate but commonly derive their hydrophilic portion from polyhydroxy or polyelhoxy structures. Ampholytic and it itlerionic surfactants are also known and arc starting to be of commercial importance. 

Griffin developed a simple equation for calculation of the HLB number of certain numbers of nonionic surfactants such as fatty acid esters and alcohol ethoxylates. For the polyhydroxy fatty the HLB number is given by the equation... 

Partial esters of fatty acids with polyhydroxy compounds of the type CH2OH (CHOH) CH2OH where n = 0-4 are the basis of a useful class of surfactants. The weak hydrophobic properties are provided by the unesterified hydroxyl group, which essentially limits the range to monoesters. In general, monoesters of lauric, palmitic, stearic and oleic... 

Griffin developed simple equations for calculating the HLB number of relatively simple nonionic surfactants. For example, for a polyhydroxy fatty acid ester ... 

Light-duty or gel dishwashing compositions containing an alkyl ether sulfate-based anionic surfactant, polyhydroxy fatty acid amide nonionic surfactant, suds boosters/stabilizers, aqueous liquid carrier, pH control agent, and acrylic copolymer thickener are disclosed in U.S. Patent 6,274,539. Viscosity as determined... 

This class of compounds is covered by a large number of application and formulation patents. Such surfactants are claimed to have superior cleaning efficiency with respect to oily/greasy and enzyme-sensitive soils. Glucamides are polyhydroxy fatty acid amides, having the typical Structure D shown in Figure 14.20. 

Metallic sulfonates, such as sodium sulfonate, are often used as emulsifiers in both water-in-oil and oil-in-water emulsions. Other emulsifiers used include ethylene oxide condensation products and derivatives of polyhydroxy alcohols such as sorbitol and sulfosuccinates for water-in-oil emulsions. For oil-in-water emulsions, soaps of fatty acids, rosins, or naphthenic acids are often used as emulsifiers. In either application, the role of emulsifiers is to change the interfacial tension at the water and oil interface. In cases where emulsification with water is undesirable, demulsifiers are used. Frequently, the demulsifiers are heavy metal soaps, such as alkaline earth sulfonates. These surfactants function by lowering emulsion stability. 

The lower molecular weight polymers of propylene oxide and propylene oxide adduct copolymers are used as surfactants, hydraulic fluids, and machine and metal-working lubricants. Propylene oxide adducts of polyhydroxy compounds, such as glycerine, trimethylolpropane, or pentaerythritol or sorbitol, are principal polyols used in making polyurethane elastomers, rigid thermal insulation, flexible foams, and coatings. 

The method selected for the preparation of a nonionic fluorinated surfactant depends on the hydrophile, which can be either an polyalkyl ether chain or a polyhydroxy group. Because oxyethylation results in a mixture of oligomers, special methods have been devised for the preparation of monodisperse surfactants. A unique group of nonionic surfactants are amphiphiles without a hydrophile. Semi-fluorinated alkanes with an oleophilic and an oleophobic segment function as nonionic surfactants in oleophilic solvents (see Section 1.8). 

Nonionic Fluorinated Surfactants with a Polyhydroxy Hydrophlle... 

Riess and co-workers [252-263] have prepared nonionic fluorinated surfactants with a polyhydroxy hydrophile by perfluoroalkylating natural products such as monosaccharides and disaccharides, pentitols, hexitols, and so forth. Per-6>-acetylglycopyranosyl bromides were reacted with 1 l-(F-alkyl)-10-undecenols,... 

Other classes of polyol surfactants have as their starting materials polyhydroxy compounds with 2-6 hydroxyl units per chain. Those hydrophilic groups include sugars, ethylene and propylene glycol, and other related materials. The surfactants are usually prepared by the esterification of fatty acids with the desired polyol, normally resulting in the formation of mixtures of mono-, di-, and often polyalkyl esters. The commercial products, therefore, may be complex mixtures of compounds whose final properties must be determined by the careful control of feedstock composition and reaction conditions. Relatively pure monoglyceride esters (>90% ot-mono) may be obtained by molecular distillation. Distilled monoesters of propylene glycol are also important in the food industry. 

---