Effect of the DPD model parameters on the transport properties of ionic liquid

Ionic liquids (ILs) and deep eutectic solvent (DES) systems are regarded as environmentally friendly alternatives to conventional toxic molecular solvents. Their tunable physicochemical properties enables amphiphilic properties to dissolve both polar and nonpolar molecules, while strong ionic pairing leads to inherently low diffusivity and high viscosity. Ab initio and molecular dynamics (MD) simulations have been widely employed to probe ionic pairing and microrheological properties. However, the charged interactions and bulky alkyl chains in ILs give rise to sluggish dynamics that span multiple time and length scales. Mesoscopic simulation frameworks that systematically coarse-grain equilibrium and dynamic features from shorter scales serve as an ideal route to studying such systems and their self-assembled mesoscale structures. In this study, we employ the dissipative particle dynamics (DPD) method to investigate how the particle number density, cutoff radius of conservative and dissipative interactions, friction coefficient, and repulsion exponent affect the transport properties of ILs (e.g. viscosity), while ensuring thermodynamic consistency based on the Flory–Huggins χ parameters. Furthermore, we compare our simulation results with rheological data measured for various IL and DES. This study is expected to provide a transferable route from IL/DES chemistry to rheology, deepening our understanding of their mesoscale properties under process-relevant conditions and accelerating material discovery.