Characterization of surfactant aggregates at solid-liquid surfaces by atomic force microscopy

Surfactants are widely used in many fields involving liquid-solid interfaces, like oil recovery, flotation and colloidal suspensions. Most key properties of solid interfaces for example wetting, agglomeration and friction properties are expression of the nanoscopic features of the adsorbed layer, like its structure and morphology.The adsorption of surfactants at the liquid-solid interface involves several physico-chemical aspects like chain interactions in solution. Similarly to what observed in the bulk, adsorption at solid surfaces often results in the self-assembly of the amphiphilic molecules into ordinate structures.Self-assembly occurs under conditions depending on bulk concentration and temperature, which affect the shape and the periodic structure of the studied amphiphilic molecules.Here atomic force microscopy is used as a direct tool to investigate the influence of the chain length, type and morphology on nucleation of ordered aggregates at a solid hydrophobic surface from a surfactant solution.