Perfluorinated Pyridinium and Imidazolium Ionic Liquids

Ionic liquids with perfluorinated side chains were prepared as hybrid materials for surface impregnation. For the cationic part, methyl and ethyl pyridinium as well as imidazolium scaffolds were used. The anions investigated were hydroxide, acetate, trifluoroacetate, triflate, triflimide, chloride, bromide, iodide, hydrogensulfate, and perfluorododecanoate. A key feature of this investigation is the finding that the use of relatively short perfluorohexyl residues as the fluorinated part of the salts is beneficial for the target compounds compared with established products, because of their lower bioaccumulativity. One compound yielded single crystals that were suitable for X-ray structure analysis, revealing a layered structure with relatively well-resolved, hard ionic domains alternating with disordered, soft perfluorinated layers. The wettability of all 30 materials was investigated by water contact angle measurements of a thin film on a glass surface. In two cases, promising contact angles (130 degrees and 140 degrees) were observed, indicating that the products might be suitable candidates for the impregnation of surfaces.