Supervisors: Dr. Uno Mäeorg
Ph.D Kristjan Saal
Opponents: Dr. Karine Mougin, University of Haute-Alsace, France
Dr. Mihkel Koel, Tallinn University of Technology
Ionic liquids are at ambient temperature liquid salts. In the present thesis the preparation of chemical organic and inorganic ionogels as a method for immobilizing ionic liquids was investigated. Immobilization of ionic liquids in solid state while retaining their extraordinary physico-chemical properties is needed for several practical applications where the fluidity of ionic liquids leads to problems related to leakage and difficulties in obtaining or maintaining a predefined physical shape of the material.
In the present thesis novel organic ionogels were prepared by mixing methacrylate type polymerized ionic liquids (PILs) with 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]; 10-75% v/v). The motivation of addition of [EMIM][BF4] was to prepare transparent and flexible materials with higher conductivity than that of neat PILs. The results of the current thesis show that by mixing PILs with conventional ionic liquid the conductivity increase about an order of magnitude (from 10-5 to 10-4 S cm-1) can be achieved.
The sol-gel process is a convenient and flexible method for the preparation of inorganic ionogels. In the current thesis hydrazinosilanes as an alternative for silyl functionalized imidazolium or ammonium ionic liquids were proposed as starting materials for inorganic chemical ionogels. The preparation of hydrazinosilanes has not been reported prior to the synthesis of 3-hydrazinopropyl trimethoxysilane carried out in the present thesis. The motivation for preparation of hydrazinosilanes were their potential advantages compared to analogous aminosilanes, like stability in broader pH range and chemical versatility due to additional amino group. The quaternization of prepared hydrazinosilane and potential applications for hydrazinium ionic liquids based ionogels need further investigations.