Role of surfactant structure on surface and foaming properties

The influence of surfactant structure on interface properties was estimated from measurements of the static and dynamic surface tension and the interface complex modulus, as obtained from an image analysis technique based on the oscillating bubble method. A simplified kinetic model of surfactants molecular adsorption at the gas–liquid interface was introduced and the rate of adsorption was determined from measurements of the dynamic surface tension. The mean life time of foams generated from bubbling air through different surfactant solutions was measured using a modified Bikerman device. The major conclusion arising from this study, as expected from basic considerations, was that the chain length of the hydrophobic part of the surfactant plays a determining role with respect to both the kinetic migration to the interfaces and the ensuing surface activity, as shown by the extent of phase delay and foam stability.