An atomic force microscopy study of asphaltenes on mica surfaces. Influence of added resins and demulsifiers

Monolayers of asphaltene and resins on the water surface have been transfer red at a surface pressure of 10 mN/m onto mica substrates using the Langmui r-Blodgett technique. Atomic force microscopy (AFM) has been used to examin e the topography of these layers. Monolayers consisting of pure asphaltene fractions provide a rigid him with a close-packed structure, while the resi ns build up a continuous open network. Mixed films of these two fractions s how that a gradual increase in resin concentration leads to an opening of t he rigid asphaltene structure towards a more resin like configuration. Incr eased aggregation when the two heavy functions are present in one film is s een as larger individual units in the AFM pictures. Addition of high-molecu lar-weight demulsifiers/inhibitors results in the same kind of influence on the asphaltene film as seen with the resins.