Triethylene glycol-based poly(1,2,3-triazolium acrylate)s with enhanced ionic conductivity

A series of cationic poly(acrylate ionic liquid)s having a triethylene glycol (TEG) spacer and a pendant 1,2,3-triazolium group is synthesized by post-polymerization sequential chemical modifications. A chloride-functionalized polyacrylate common precursor is first obtained by reversible addition-fragmentation chain transfer (RAFT) polymerization of a TEG-based chloride-functionalized acrylate. Sequential azidation, copper-catalyzed azide–alkyne cycloaddition with 1-pentyne and alkylation of the resulting 1,2,3-triazole by methyl iodide affords a poly(acrylate ionic liquid) having pendant 3-methyl-4-propyl-1,2,3-triazolium iodide groups. Further anion metathesis with three different fluorinated salts yields a series of 1,2,3-triazolium-based PILs with distinct counter anions. The polymer precursors and resulting poly(1,2,3-triazolium ionic liquid)s (PTILs) are characterized by 1H NMR spectroscopy, size exclusion chromatography (SEC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and broadband dielectric spectroscopy (BDS). Well-defined PTIL derivative with bis(trifluoromethane)sulfonimide anion (Mn = 113,600 g mol−1 and Đ = 1.23) exhibits the lowest glass transition temperature (Tg = −36 °C), the highest thermal stability (Td10 = 321 °C) and the highest anhydrous ionic conductivity (σDC = 1.1 × 10−5 S cm−1 at 30 °C) of the series.