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. (C) 2004 Elsevier B.V. All rights reserved.