(355g) Structure and Dynamics of Model Asphaltene Molecules at an Oil-Water Interface

Asphaltenes are a collection of various high molecular weight, aromatic molecules found naturally in petroleum that are of great concern in the recovery of oil reserves. The presence of asphaltenes strongly stabilizes oil and water emulsions and complicates separation processes. For example, when oil and water emulsions are formed for the purpose of desalination, asphaltenes stabilize those emulsions such that regaining pure crude becomes more challenging. It is well known that the interfacial behavior of asphaltenes, both thermodynamically and rheologically, are responsible for this stabilizing effect, but it is not well understood what structures within the collection of molecules that constitute natural asphaltenes give rise to this unique interfacial behavior. By formulating model asphaltene molecules and systematically investigating their interfacial behavior, one can identify what particular molecular architectures in natural asphaltenes are critical for their stabilizing properties. Ultimately, a complete understanding of how the structure of asphaltenes influences their interfacial behavior makes it possible to formulate new, informed strategies for controlling oil and water emulsion stability. We will present results from an investigation of the interfacial thermodynamics and rheology of a particular class of model asphaltene molecules, and discuss the consequences for natural asphaltenes found in crude oil reserves.