Permeability of Vesicles for Imidazolium-Based Ionic Liquids in Aqueous Solution: A Molecular Dynamic Simulation Study

Self-assembly of ionic liquids (ILs) in solution has attracted wide attention due to their potential applications in chemical and biological investigations. In this study, the aggregation behavior of 1-alkyl-3-methylimidazolium alkyl sulfate in aqueous solution was investigated by molecular dynamics simulations. The simulations reveal that interactions between tail groups play a dominant role in stabilizing the vesicle. The permeability of the vesicle was further studied, and the exchange rate of water molecules is determined by the thickness of membrane. Besides thickness, arrangement of alkyl chain of ILs in the vesicle structure influences the permeability. The interdigitated structure of tail groups in the [C(8)mim][C12SO4] system decreases the water exchange rate compared with the similar system of [C(12)mim][C8SO4]. Furthermore, the hydrogen bonding interaction and orientation analysis indicate that the orientation of the imidazolium ring provides the empty positions for water-anion interactions and promotes the water molecules to approach the hydrophobic region. These results suggest that vesicle with excellent permeability properties could be obtained by screening the hydrophilic and hydrophobic of ILs and they might be beneficial for the application in separation and drug delivery process.

Automated summary

The self-assembly behavior of ionic liquids in aqueous solution was studied through molecular dynamics simulations, revealing the dominant role of interactions between tail groups in stabilizing vesicles and the influence of membrane thickness and alkyl chain arrangement on vesicle permeability. The interdigitated structure of tail groups reduced water exchange rate, while the orientation of the imidazolium ring promoted water molecules approaching hydrophobic regions. These findings suggest the potential for obtaining vesicles with excellent permeability properties by screening the hydrophilic and hydrophobic properties of ILs for applications in separation and drug delivery processes.