Molecular Dynamics Simulation Of Ionic Liquid-water Mixtures

Room temperature ionic liquids （RTILs）is always considered as the most idealalternatives to volatile organic solvents in twenty-first Century. Due to as a novelgreen medium, it has low steam pressure,less volatile,strong solubility,polarityadjustable liquid process,a wide range of special physical and chemical properties.With the in-depth research,which should be used in organic reations,polymerchemistry, materials chemistry,electrochemistry,analysis of many fields of chemistryand separation technology, had been attached great importance to international.It hasbeen proven that both hydrophilic and hydrophobic ionic liquids can absorb somewater which will strongly affect the physico-chemical properties andsolubility.Therefore,the theoretical investiment is very important for bothfundamental research and practical application.Many researchers have studied ionicliquids through theroy and experiment.In this paper,the interaction between watermolecules and ionic liquids has been systematically investigated by moleculardynamics simulation.In this paper, it is applied to molecular dynamics simulation using the adjustedAmber99force （Tinker）, under the isothermal isobaric （NPT） ensemble simulation,performed to interaction between hydrophilic imidazolium-based ionic liquids[bmim][BF₄], hydrophobic [bmim][PF₆] with H2_O mole fraction of0.25,0.5,0.75,0.8,0.83,0.89for the simulation. It obtained the cohesive density,enthalpy of vaporization,radial distribution function,system density,excess molar volume and thermodynamicand kinetic properties in addition. Further, it explored the microscopic structure ofliquid imidazolium ionic liquid in a large number of ionic interactions, watermolecules forming hydrogen-bond network structure, and predicted to the effectionsof the presence of water molecules on the macroscopic properties of imidazoliumionic liquids.In view of the hydrophobic and hydrophilic ionic liquid mixtures is not easy todissolved, the hydrophilic and hydrophilic ionic liquid mixed with water is difficult tocontrol, and affact to the physics-chemical properties of mixed ionic liquid. Therfore,we exployed the1-3-methyl imidazole salt （[bmim][BF₄]/[bmim][PF₆]）mixture to formed a two binary mixtures, then it mixed with water in the molarfraction of0.5,0.75,0.8,0.83,0.89to formed three binary mixtures. In the end, itobtaied cohesive density,enthalpy of vaporization,radial distribution function,systemdensity,excess molar volume,thermodynamic and kinetic properties besides. Further itreveals the difference microscopic properties of the interaction between mixturecomponents, and single component.The ivestigation on mixture ionic liquids and the interaction between mixtureionic liquids with water can preliminary eplore the micromechanism of interaction,thestate of water molecules,provide some intial hints as to the nanostructuralevolution,predict the presence of water molecules affact to ionic liquids onviscosity,conductivity,surface properties,the hydropphilic and solubility.In addition,the ionic liquid multivariate mixed system research, can wealthily explain ionicliquids in the microscopic morphology, structure and its change process, is avail toestablish mixing and separation techniques of multivariate system. This thesis isprovied the theoretical basis to imidazole ionic liquids for better application in theorganic synthesis, extraction separation, catalytic electrolysis and nano materials, etc.