A disjoining pressure study of foam films stabilized by mixtures of a nonionic (C12DMPO) and an ionic surfactant (C12TAB)

This work is a continuation of a previous study [Langmuir 23 (2007) 5315–5323] of aqueous foam films stabilized by surfactant mixtures consisting of a cationic and a nonionic surfactant. In both studies a thin film pressure balance was used to investigate the disjoining pressure Π as a function of the film thickness h. With the resulting Π–h curves the surface charge densities q0 of the foam films were determined by fitting them with the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. Our previous study demonstrated that mixing the nonionic surfactant β-dodecylmaltoside (β-C12G2) and the cationic dodecyl trimethylammonium bromide (C12TAB) allows one to tune q0 and thus the type of foam film. In the present study the nonionic surfactant dodecyldimethyl phosphineoxide (C12DMPO) instead of β-C12G2 was used and C12DMPO/C12TAB mixtures in a concentration range from 0.1 to 2.0 cmc were studied at mixing ratios of C12DMPO:C12TAB = 1:0, 50:1, 1:1, 1:50, 0:1. The results are compared with those of the β-C12G2/C12TAB mixture and are discussed in terms of surface charge densities.

A disjoining pressure study of foam films stabilized by mixtures of a nonionic (dodecyldimethyl phosphineoxide, C12DMPO) and an ionic surfactant (dodecyl trimethylammonium bromide, C12TAB).Figure optionsDownload high-quality image (89 K)Download as PowerPoint slide