Dispersion Stability\nMechanism of Asphaltene in Deep\nEutectic Solvents through Multiresolution Simulation Approaches

Elucidating the nonbonded interactions between model\nasphaltene\nstructures and deep eutectic solvents (DESs) holds both theoretical\nintrigue and experimental significance. Through DFT simulation approaches,\nthis study demystified the configurational features and intermolecular\ninteraction dynamics of solvation utilizing island- and archipelago-type\nmodel structures, representative of asphaltene compounds. The present\nstudy investigates asphaltene dissolution mechanisms in DESs and predicts\nthe solubility parameters (Hansen) of asphaltene and DESs using the\nHSPiP model and the COSMO-RS method. The frontier molecular orbitals\n(FMOs) and interaction energy shed light on the solvation effects\nvia the intricate nature of asphaltene–DES bonding through\ndifferent cluster conformers. It reveals that DES1 (thymol and diphenyl\nether, 1:1) and DES2 (thymol and biphenyl, 2:1) exhibited stronger\ninteraction energy and stability. Employing Bader’s theory\nof quantum theory of atoms in molecules (QTAIM) analysis highlighted\nthe molecular interaction critical for enhancing asphaltene dispersion\nin nonionic-type DESs. Furthermore, the employment of reduced density\ngradient (RDG) isosurfaces facilitated the identification of interaction\ntypes, revealing that these interactions manifest as either dispersive\nor hydrogen bonding, which was found to be aligned with Hansen solubility\nparameters too. Among the studied, DES1 (thymol/diphenyl ether) exhibited\na strong interaction with the archipelago-based model structure of\nasphaltene compared to the island-type model structure. The solubility\nparameter (SP) of the asphaltene model structure is 22.12 MPa<sup>1/2</sup>, which is close to the solubility parameter of DES1 (21.90\nMPa<sup>1/2</sup>). which results in higher dispersion.