Study of Ion Transport in Novel Protic Polymerized Ionic Liquids and Composites

Abstract

In this work, a novel protic polymerized ionic liquid [PSTFSI][Im] is synthesized. The [PSTFSI][Im] polymer presents moderate ionic conductivity and evidences proton activity. Incorporating protic ionic liquid (Protic IL) [MIm][TFSI], the composites present enhanced ionic conductivity, up to 10 −3 S cm −1 at 120 °C upon addition of 60 wt% [MIm][TFSI]. It is found that the [PSTFSI][Im] polymer matrix can promote ion dissociation of the [MIm][TFSI] IL, leading to a larger cation/anion relative mobility compared to the neat Protic IL. This work demonstrates the potential of protic PolyIL as a polymer matrix for proton conductors.

Effect of Fumed Silica on Ion Conduction in Proton-Conducting Nanocomposites

“…were confirmed by NMR spectroscopy as reported in our previous studies, 11,25 where no impurity peaks can be identified from the 1 H/ 19 F/ 13 C NMR spectra.…”

“…Nanosilica (Sigma-Aldrich, 14 nm), acetonitrile (Sigma-Aldrich, ≥99.8%), and methanol (Sigma-Aldrich, ≥99.8%) were commercially available and used without any further pretreatment. [PSTFSI]­[Im] and [MIm]­[TFSI], as shown in Figure , were synthesized as per published methods . The purities of [MIm]­[TFSI] and [PSTFSI]­[Im] were confirmed by NMR spectroscopy as reported in our previous studies, , where no impurity peaks can be identified from the 1 H/ 19 F/ 13 C NMR spectra.…”

“…[PSTFSI]­[Im] and [MIm]­[TFSI], as shown in Figure , were synthesized as per published methods . The purities of [MIm]­[TFSI] and [PSTFSI]­[Im] were confirmed by NMR spectroscopy as reported in our previous studies, , where no impurity peaks can be identified from the 1 H/ 19 F/ 13 C NMR spectra.…”

“…Particularly, PolyILs might be a competitive matrix alternative for next-generation proton-exchange membranes. , Our previous study reported PolyILs/PILs composites with a high anhydrous ionic conductivity of 10 –3 S/cm above 100 °C. The relationship between the chemical structure and ion conduction in electrolyte materials has been investigated by solid-state NMR spectroscopy and other characterization techniques. , Poly­(diallyldimethylammonium) (PDADMA) backbone-based cationic PolyILs were mixed with imidazolium-based PILs to prepare composite membranes with single-anion and bi-anion species, with the intention to explore the effect of the anion chemistry on proton conduction . The composite with both [TFSI] and [OTf] anion showed greater ionic conductivity and cation/anion diffusivity than those with either anion alone.…”

“…The composite with both [TFSI] and [OTf] anion showed greater ionic conductivity and cation/anion diffusivity than those with either anion alone. In the case of the composites based on the anionic protic PolyIL, poly­([4-styrenesulfonyl­(trifluoromethylsulfonyl)­imide] [imidazolium]), [PSTFSI]­[Im], the results showed that the PolyIL matrix can improve ion dissociation in the PIL . The ionic conductivity of composites was enhanced as the PIL content increased, whereas the mechanical strength of composites was diminished due to the strong plasticization effect of the PIL.…”