1,2,3-Triazolium-Based Poly(ionic liquid)s with Enhanced Ion Conducting Properties Obtained through a Click Chemistry Polyaddition Strategy

Abstract

1,2,3-Triazolium-based poly(ionic liquid)s containing a triethylene glycol spacer were synthesized from the polyaddition of an α-azide-ω-alkyne monomer by copper-catalyzed azide–alkyne cycloaddition (CuAAC) followed by quaternization reactions with alkyl halides and subsequent anion exchanges with different fluorinated salts. A detailed structure–property relationship for solubility, thermal stability, and ionic conductivity was investigated by means of 1H NMR spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and broadband dielectric spectroscopy (BDS). One of these poly(ionic liquid)s with a methyl substituent and bis(trifluoromethylsulfonyl)imide anion exhibits an ionic conductivity of 2 × 10–5 S cm–1 at 30 °C, which is on par with the best PILs with side-chain charge carriers reported so far and is much higher than any previously reported ionenes. The straightforward synthesis along with the broad structural design and enhanced properties of this new class of poly(ionic liquid)s offer both fundamental and applicative perspectives.