Synthesis, characterization and diverse applications of new ionic liquids containing cyclic phosphazenes

In this study, firstly, tetrachloromono(4-fluorobenzyl)-spiro phosphazenes (1-2) were synthesized from the reaction with diamines of trimmers and afterwards, the new fully substituted mono (4-fluorobenzyl)-spiro phosphazene compounds containing (dimethylamino)ethoxy, (dimethylamino)propoxy and pyridylmethoxy chains were synthesized from the reaction with amino-alcohols of these derivatives (3-7). The substituted nitrogens were quaternized to yield the polyiodine salts by reaction with CH3I of the synthesized compounds (8-12) and new phosphazene-based ionic liquids (ILs) (13-22) were obtained by reaction with LiN(SO2CF3)2 and NaBF4 of the polyiodine salts. Structures of the synthesized phosphazene-based ILs were determined using elemental analysis, FT-IR, one-dimensional (1D) 1H-, 13C- and 31P-NMR techniques. Thermal properties of these ILs were determined using thermal analysis (TA) techniques, and their viscosities were determined using a cone-plate viscometer. On the other hand, dielectric properties of these new ILs, their tribological properties for use as friction and wear resistant materials, their potential use as electrolyte solvents in lithium-ion batteries and their usage as a second gate layer as the electrolyte in organic field-effect transistors (OFET), were investigated. In conclusion, the dielectric values of the newly synthesized phosphazene-based ILs were found to be quite high, and electric double layer formation was observed at low frequencies. Consequently, the the produced OFETs were found to operate at low voltages due to the high dielectric effect of phosphazene-based ILs. As a result of the tribology studies of phosphazene-based ILs, no effective lubrication between the ball and the plate has occurred. When compound 17 was used as an electrolyte additive, the capacity loss was reduced by the number of charge/discharge cycles of the lithium ion battery, while the use of the other phosphazene-based ILs led to an increased capacity loss.