Foaming and emulsifying properties of fatty acids neutralized by tetrabutylammonium hydroxide

Our paper aims at determining the interfacial, foaming and emulsifying properties of a series of dispersions made of long chain fatty acids (carboxylic acids) and hydroxyl derivatives neutralized by tetrabutylammonium hydroxide (TBAOH). Those fatty acids were myristic, palmitic and stearic acid as saturated fatty acids and juniperic and 12-hydroxystearic acid as the hydroxyl fatty acids. All these systems are already known to form micelles in water at room temperature. Here, we determined the critical micelle concentration (CMC) for all those systems using electrical conductivity. Foaming and emulsifying properties were then studied below and above the CMC. Relatively stable emulsions can be produced above but not below the CMC. There is a noticeable effect of the alkyl chain length and the presence of a hydroxyl group. The foamability is good but the foam stability is low in all cases above the CMC. Below the CMC, the foamability depends on the fatty acid and foams destabilize very quickly. Thus, the use of TBAOH to disperse fatty acids in water at room temperature allows using long chains fatty acids and hydroxylated derivatives for the production of emulsions and foams, the stability of which can be modulated.