Interfacial dilational rheological property and lamella stability of branched alkyl benzene sulfonates solutions

The dynamic dilational properties of branched alkyl benzene sulfonates at the air–water and decane–water interfaces were investigated by drop shape analysis, and their lamella stability was measured. The influences of time, dilational frequency, and bulk concentration on surface dilational elasticity and dilational viscosity were expounded. The results show that the molecular interaction controls the nature of adsorption film during lower concentration range and the film behaves elastic in nature. During higher concentration range, the diffusion-exchange process controls the dynamic dilational properties and the surface film shows remarkable viscoelasticity. An increase in hydrophobic chain length enhances the molecular interaction, which results in the increase of dilational parameters and lamella stability. The data correlation suggests that the ability to form a stable lamella is linked to the intrinsic surface dilational elasticity.