(284b) Structural and Dynamical Properties of Deep Eutectic Solvents Confined in Slit Pores

Molecular dynamics (MD) simulations were performed to study the structure and dynamics of a deep eutectic solvent (DES) inside slit-like nanopores. The DES studied was a mixture of choline iodide (a quaternary ammonium salt) with glycerol (a polyol) with a molar ratio of 1:3, while the model nanoporous materials considered were titania (rutile) and graphitic slit-like nanopores with two pore widths, 5.2 nm and 2.5 nm. DESs share many of the physical and chemical properties of room temperature ionic liquids (ILs) while being considerably cheaper and (mostly) nontoxic. In particular, the DES choline iodide-glycerol has demonstrated promising performance when used as electrolyte in dye-sensitized solar cells (DSSCs), but a fundamental understanding of the properties of these systems inside nanopores is still lacking. Our results show that the properties of the DES choline iodide-glycerol confined in nanopores can be significantly affected by the pore width and the chemical composition of the pore walls. The properties of the confined DES are especially affected when choline iodide and glycerol can form hydrogen bonds with atoms in the pore walls. This situation can lead to the formation of spatial inhomogeneities in the molar ratio of choline iodide and glycerol inside the nanopores. As a result, important differences were observed in the structure and dynamics between DESs confined in graphitic and titania nanopores of different pore widths, and between those systems and the bulk DES.