Solvation structures of water in trihexyltetradecylphosphonium-orthoborate ionic liquids
- Applied Physical Chemistry, Department of Chemistry, KTH Royal Institute of Technology, SE-100 44 Stockholm (Sweden)
- Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm (Sweden)
- Chemistry of Interfaces, Luleå University of Technology, SE-971 87 Luleå (Sweden)
- System and Component Design, Department of Machine Design, KTH Royal Institute of Technology, SE-100 44 Stockholm (Sweden)
Atomistic molecular dynamics simulations have been performed to investigate effective interactions of isolated water molecules dispersed in trihexyltetradecylphosphonium-orthoborate ionic liquids (ILs). The intrinsic free energy changes in solvating one water molecule from gas phase into bulk IL matrices were estimated as a function of temperature, and thereafter, the calculations of potential of mean force between two dispersed water molecules within different IL matrices were performed using umbrella sampling simulations. The systematic analyses of local ionic microstructures, orientational preferences, probability and spatial distributions of dispersed water molecules around neighboring ionic species indicate their preferential coordinations to central polar segments in orthoborate anions. The effective interactions between two dispersed water molecules are partially or totally screened as their separation distance increases due to interference of ionic species in between. These computational results connect microscopic anionic structures with macroscopically and experimentally observed difficulty in completely removing water from synthesized IL samples and suggest that the introduction of hydrophobic groups to central polar segments and the formation of conjugated ionic structures in orthoborate anions can effectively reduce residual water content in the corresponding IL samples.
- OSTI ID:
- 22678987
- Journal Information:
- Journal of Chemical Physics, Vol. 145, Issue 6; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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