Water surfactant systems, alkyl polyglycosides

The development of cosmetic microemulsion cleansers with alkyl polyglycosides (APG) was described by Forster et al. [4]. This class of non-ionic surfactants has excellent environmental and skin compatibility. Cosmetic cleanser multicomponent systems are required to have good foaming and cleansing performance. Figure 8.3 shows a pseudo-ternary phase diagram of a five-component formulation. It consists of water, the oil dioctyl cyclohexane (DOCH), the non-ionic surfactant C12/14-APG, the anionic surfactant fatty alcohol ether sulphate (FAES) and the co-surfactant sorbitan monolaurate (SML). The phase diagram... 

Similarly to anionic surfactants, alkyl polyglycosides react to the addition of cosolvents that increase the solubility of the surfactant in the oil phase. In the decane-water-alkyl polyglycoside system, the addition of the cosolvent i-butanol results in a drastic reduction in the interfacial tension between oil and aqueous phase and, hence, in the formation of a third phase, the microemulsion [70]. As expected, the range in which this three-phase microemulsion exists is only slightly dependent on temperature and, in contrast to anionic surfactants, is also hardly affected by electrolytes [70]. Systematic investigations of the phase behavior confirm these initial results for a number of simple hydrocarbons from hexane to hexadecane and aromatics [71,72]. 

This provides for interesting applications because, in contrast to fatty alcohol ethoxylates, temperature-stable microemulsions can be formed with alkyl polyglycosides. By varying the surfactant content, the type of surfactant used, and the oil/water ratio, microemulsions can be produced with custom-made performance properties, such as transparency, viscosity, refatting effect, and foaming behavior. In mixed systems of, say, alkyl ether sulfates and nonionic coemulsifiers (alkyl polyglycoside), extended microemulsion areas... 

A model formulation was selected consisting of 20% emulsifier mixture (alkyl polyglycoside and GMO), 20% perfume oil, less than 2% oil (dicapryl ether and octyldodecanol), and water. The GMO was chosen as coemulsifier because it proved to be most suitable for nonpolar oil. No microemulsion is formed if C,2/i4 alkyl polyglycoside and GMO are used as emulsifiers for this system. It was reported that the oil solubility of the surfactant in systems... 

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