THEORETICAL-MODELS FOR DYNAMIC DILATIONAL SURFACE-PROPERTIES OF BINARY SURFACTANT MIXTURES

A theoretical description for the dynamic surface properties of binary surfactant mixtures containing (i) two insoluble surfactants, (ii) tw o soluble surfactants, or (iii) one insoluble and one soluble surfacta nts was developed, We showed that previously reported expressions for surface dilational modulus do not correctly account for surface compos itional dependence, New expressions, which take into account compositi on effects explicitly, for the frequency-dependent dilational visco-el astic modulus (based on diffusion-controlled adsorption) for these thr ee systems were obtained, In the limit of high surface deformation fre quencies, the surface dilational elasticity epsilon(0) for the binary mixtures considered here reduces to epsilon(0) = -(partial derivative sigma/partial derivative Gamma(1))(Gamma 2T)Gamma(1) - (partial deriva tive sigma/partial derivative Gamma(2))(Gamma 1,T)Gamma(2). (C) 1995 A cademic Press, Inc