Study On Preparation Of EMIC And AlCl₃-EMIC Room Temperature Ionic Liquids

As a new functional material, room temperature ionic liquid shows a promising prospect in the fields of new materials, biotechnology, green chemistry and electrochemical industry. AICl3-EMIC room temperature ionic liquid attracts a lot of concentration due to its wide range of chemical processes, adjustable Lewis acidity and high conductivity. However, there are few reports about the industrial production and testing standard about EMIC and also the refinement of AICl3-EMIC.As foundation of tritium barrier coating prepared by electrodeposition through AICl3-EMIC, the industrial production and process optimization of EMIC synthesis, the analysis methods of EMIC and the preparation of AICl3-EMIC of high purity are of great importance. Therefore, these problems are focused on in this paper.EMIC was synthesized sucessfully through reactants of various purity(domestic and imported). By orthogonal experiment of ratio of reactants, temperature and time, we aquired the best conditions for synthesis:MIM:Chloroethane=1:4.5、T=80℃、 time=45h.Karl Fischer-Coulomb Titration is employed in the detection of water content in EMIC and raw materials. Two methods were put forward to get the water content of EMIC:dissolved in ethanol or injected in a solid sample vessel. The results showed that MIM have a high capacity of water absorption while cyclohexane have not. By treating MIM with molecular sieve, the water content of EMIC is decreased to700ppm from13000ppm.The structure of EMIC was verified by NMR. The unreacted MIM, whose content is about6mol.%～7mol.%, was found to be the reason why some samples cann’t solidify.HPLC was also used to test and quantitively detect EMIC and MIM. The wash solvent is ACN:water=4.5:5.5(0.1%acetic acid). stationary phase is C18. The UV absorption per ppm of EMIC and MIM is300and700, respectively. The appropriate concentration for the test is0.1ppm～20ppm(MIM) and1～10ppm(EMIC).The refinement of AICl3-EMIC ionic liquid with Al wires is important for the deposition. In this paper, the refinement of acidic AICl3-EMIC (2:1) was studied. The cyclic voltammograms with three-electrode system, viscosity and electronic conductivity of the ionic liquid were measured before and after the refinement. The galvanostatic electrodeposition of Al on Cu was carried out using a two-electrode system. SEM and EDS were employed to examine surface morphologies and components of refining Al wires and electrodeposited Al coatings. The results show that the viscosity and electronic conductivity varied little after the refinement, however, the current efficiency and Al-coating quality increased. After a168h-refinement, a dense and adhesive aluminum coating can be electrodeposited. We also discused the mechanism of the refinement.