Study On The Influence Of Organic Solvents On The Conductivity Of Ionic Liquids And Applications

Room temperature ionic liquid has a good ionic conductivity due to its composition of ions. Recent researches showed that when the room temperature ionic liquids absorbed water or organic solvents, the ionic conductivity would have a significant change. This thesis focused on the influence of alcohol on the conductivity of ionic liquid (BmimPF6). The conductivity of BmimPF6 containing alcohols were detected experimentally and calculated by molecular dynamics method. Base on the conductivity changes of ionic liquid/polymer gel, a novel organic vapor gas sensor was prepared.Obtained preliminary results are:(1) Through the standard addition method, the conductivity of pureBmimPF6 systems and alcohol-BmimPF6 mixture were determined. The results showed that the conductivity was influenced by the temperature and the solvent properties. In the low concentration range of the alcohols, the conductivity of BmimPF6 showed a good linear relationship with the concentration of the alcohols.(2) Molecular Dynamics Simulation was also used to estimate theconductivity of pure BmimPF6, and its mixture with alcohol. Firstly, using the Gaussian98 software, based on RHF/6-31G (d) and MP2/cc-pVTZ (-f) basis set, the optimized structure and the atomic charges of the ions of BmimPF6 and the alcohols were obtained respectively. And then, the molecular dynamics Simulation were carried out using Materials Explorer 4.0 program. The results showed that the volume, the conductivity and the diffusion coefficient of BmimPF6 increased with adding of alcohol. The conductivity value of ionic liquids obtained by simulation is closed to experimental values. From the radio distribution study, we believed that the increasing of conductivity maybe due to the hydrogen bond between the alcohol molecular and the anion of BmimPF6.(3) A new type of conductivity-type gas sensor based on the Ionic liquid / polymer gel was prepared, which based on the different conductivity of Ionic liquid / polymer gel in various atmospheres. Preliminarily investigation on the influence of the ionic liquid content, temperature was also conducted. The optimized sensor showed a good linear response to the different concentration of ethanol, acetone and acetonitrile.