Asphaltene association in solution has been studied extensively using methods such as vapor-pressure osmometry and neutron scattering. These methods give relative data on association asa function of solvent strength, temperature, and concentration, but interpretation of the resultsis hampered by the polyfunctional nature of asphaltenes and the distribution of molecular
weight.In this
work,
we present data on association of representative model structures for asphaltenes,as measured using vapor-pressure osmometry in
o-dichlorobenzene at 75-130
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C, and using small-angle neutron scattering in toluene. A series of compounds
were synthesized based on the four-ring aromatic compound pyrene. The synthetic compounds
were designed to give interactionsbet
ween aromatic rings, alkyl chains, and selected functional groups through aromatic interactions, hydrogen bonding, and polar interactions. Even in this strong solvent, polar interactionsbet
ween oxygen functional groups gave average molecular
weights of up to t
wice the true value,indicating dimer formation. An alkyl pyrene compound, dipyrenyl decane, gave much lesssignificant association. Pyrene itself exhibited little or no self-association.