New non-ionic surfactants from lysine and their performance

Abstract

In this paper a new class of multichain non-ionic surfactants based on lysine with two octyl, decyl, dodecyl or tetradecyl chains and one polydispersed polyoxyethylene diethanolamide head group are introduced. Measurements at air/water interface and bulk solution of surface-active properties such as surface tension and critical micelle concentration were made.These compounds were obtained by condensation of the corresponding long chain Nα, N£diacyl lysine with a polydispersed oxyethylene diethanolamine which was prepared in our laboratory. A preliminary study of their water solubility properties is also described. The surface-activeproperties were evaluated by measuring the variation of surface tension and the formation of apresumable CMC as a function of concentration in the aqueous solution. All compounds were soluble in water up to 0.5% (w/v). They showed normal surface tension values in water solutionand presented higher CMC than classical polyoxyethylene alcohols non ionic surfactants with the same number of carbon atoms in the hydrophobic moiety. In this series when each chain is increased by four methylene units, the CMC falls to about one-hundreth of its previous value.