Microstructural Characterization of Asphaltenes on Surface

Crude oils contain a distribution of molecules with diverse chemical structures and molecular weights. Asphaltenes are considered the most problematic of these structures. We have investigated the adsorption and aggregation of asphaltenes on surfaces using scanning probe microscopy. Modifying the chemical properties of surfaces using self-assembled monolayers (SAM) can change the wettability and adsorption characteristics of molecules. We have investigated adsorption of asphaltenes on gold substrates modified using dodecanethiol SAM. The molecular characteristics and thickness of the monolayers were determined using Fourier Transform infrared (FT-IR) spectroscopy and ellipsometry, respectively. The results showed that SAM inhibits the adsorption of asphaltenes on surface. To investigate the morphology of asphatlene aggregates, we used atomic force microscopy (AFM). In addition to qualitative observations of structural changes, quantitative changes in adhesion and contact potential differences (V CPD) of asphaltene aggregates as a function of temperature were also carried out.