In this study, two groups of functionalized aliphatic and aromatic ILs with the same anions were synthesized and used as asphaltene dispersants. The quartz crystal microbalance and ultraviolet spectroscopy were used in this study, and the results obtained from these two techniques were in relatively good agreement with each other. The results showed that aromatic ILs generally possess better inhibitory performance than aliphatic ones. The molecular structure of IL anions also greatly influenced the dispersion of asphaltenes in a toluene solution. It seems that π-π interactions between asphaltene molecules and aromatic cations represent the main cause of the better performance of aromatic ILs. This hypothesis was also confirmed by observing the high dispersion ability of a maleate anion, which has a carbon-carbon double bond, compared to other studied anions.
