Ch2ch2oh

Ester amide

Alkanolamides have been largely used in household detergent products; their consumption has now significantly declined because of the extensive use of alkyl ethoxylated detergent products. Because of their foam-boosting and viscosity-enhancing capacity in the presence of anionics, alkanolamides are also usefully incorporated in personal care, especially in shampoos.

Ethoxylated Alkanolamides

Reaction of an alkanolamide with ethylene oxide leads to an ethoxylated amide. R CO NH (CH2CH20)n H Polyethoxylated monoal kan o lamide

It is more expensive than its corresponding ethoxylated alcohol and has therefore restricted usage. The benefits of thickening, foam stabilization, and dispersibility are exploited in personal-care cleansers.

Esters

In this surfactant class, there are five major subcategories to be considered:

1. Ethoxylated fatty acids

2. Glycol esters, glycerol esters, and ethoxylated derivatives

3. Sorbitan esters and ethoxylated derivatives

4. Alkyl carbohydrates esters

5. Triesters of phosphoric acid

Ethoxylated Fatty Acids

This class of surfactants comprises mono- and diesters that result from the reaction of fatty acids with either ethylene oxide or polyethylene glycol.

PEG fatty acid diester

Given their outstanding emulsifying properties, ethoxylated fatty acids are useful in domestic and industrial detergents, more especially in degreasing compositions. If properly balanced, combinations of esters with low and high ethoxylation provide excellent emulsi-fiers for creams and lotions. They are also used as mild cleaners or viscosifying agents (e.g., PEG-150-distearate). In cosmetics (shampoos), less water-soluble grade (i.e., ethyl-ene glycol monostearate) is used as a pearlescent agent.

Glycol Esters, Glycerol Esters, and Ethoxylated Derivatives

A common point among the surfactants grouped in this class and the following two classes (sorbitan esters and alkyl carbohydrates esters) is that they all derive from the condensation reaction of a polyhydroxyl compound (e.g., glycol, glycerol, sorbitol, sucrose,) with a fatty acid. Some of them can be directly extracted from natural sources. The resulting esters can be additionally ethoxylated to increase their HLB value and, thereby, their solubility in water.

These surfactants show poorer wetting and foaming properties in comparison with alcohol-derived nonionics. Emulsifying properties are excellent. In general, esters and lower ethoxylates are appropriate for w/o dispersions whereas higher ethoxylates are more suitable emulsifiers for o/w dispersions.

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