Previous experimental studies have highlighted the effectiveness of DCAs containing quaternary ammonium ions due to relatively strong cation-π interactions with the aromatic deposit. However, we are not aware of any studies accounting for a zwitterionic structure, comprising a counterionic functional group (such as the carboxylate anion) to constitute a neutral molecule. The zwitterionic surfactant also contains a phenyl group and an alcohol group, which will extend the range of possible binding modes through π-π and OH-π interactions, which is expected to lead to stronger adsorption. The molecular weight of the PIBSI and zwitterionic surfactants are 830 g mol -1 and 769 g mol , respectively, which is close to that found for commercial fuel DCAs. PIBSI is known to form inverse micelles in nonpolar solvents, with aggregation numbers ranging from 3-5. Likewise, ionic-functionalised PIB (similar to our zwitterionic surfactant) also forms inverse micelles, generally with larger aggregation numbers of 4-14 depending on the cation and anion combination. However, as in most previous free energy studies of surfactants, we only consider single-molecule adsorption to understand the pure thermodynamics of adsorption. Likewise, we focus on the case in which the deposit precursor is dissolved in the base fuel, where the deposit-DCA interactions are not affected by metallic surfaces.