Foaming properties of nonionic detergents

The foam formation and foam stability of aqueous solutions of polyoxyethylene tridecanols, t-octylphenols, nonylphenols, n-dodecanols, and n-octadecanols have been determined as a function of ethylene oxide chain length. In general nonionic detergents form unstable foams; the most stable foams formed by nonionic detergents are comparable to that of sodium dodecylbenzene sulfonate in the absence of foam promoters. In each homologous series of a nonionic detergent the foam formation and foam stability pass through a max at a critical hydrophilic-hydrophobic balance (CHHB). It is shown that the CHHB corresponds to conditions of minimum foam drainage and max resistance to film rupture. Paper presented in part at the 34th National Colloid Symposium, Lehigh University, Bethlehem, Pa., 1960.