Acrylate Functionalized Tetraalkylammonium Salts with Ionic Liquid Properties

Abstract

Acrylate functionalized ionic liquids based on tetraalkylammonium salts with terminal acrylates- and methylacrylates were synthesized. Melting points and ionic conductivity of twenty compounds in six groups were determined. Within one group the effect of three different counterions was investigated and discussed. The groups differ in cationic structure elements because of their functional groups such as acrylate and methacrylate, alkyl residues at the nitrogen and number of quaternary ammonium atoms within the organic cation. The effect of these cationic structure elements has been examined concerning the compiled parameters with a view to qualifying them as components for solid state electrolytes. The newly synthesized ionic liquids were characterized by NMR and FTIR analysis. The exchange of halide ions like bromide as counter ions to weakly coordinating [PF₆]⁻, [OTf]⁻ or [TFSI]⁻ reduces the melting points significantly and leads to an ion conductivity of about 10⁻⁴ S/cm at room temperature. In the case of the dicationic ionic liquid, an ion conductivity of about 10⁻³ S/cm was observed.

Keywords

• ionic liquid
• room temperature molten salt
• electrolytes