Unconventional poly(ionic liquid)s combining motionless main chain 1,2,3-triazolium cations and high ionic conductivity

Abstract

We report the synthesis of two novel α-azide-ω-alkyne monomers with short n-hexyl and diethylene glycol spacers. Their polyaddition by both copper(I)-catalyzed and thermal Huisgen azide–alkyne 1,3-dipolar cycloaddition followed by alkylation using N-methyl bis(trifluoromethylsulfonyl)imide affords the corresponding 1,2,3-triazolium-based poly(ionic liquid)s. Their physical, ion conducting and electrochemical properties are discussed based on the chemical structure of the spacer and the regiochemistry of the 1,2,3-triazolium groups. These novel polyelectrolytes combine motionless main chain 1,2,3-triazolium cations with low glass transition temperature (T_g = −38 °C), high ionic conductivity under anhydrous conditions (σ_DC = 1.0 × 10⁻⁵ S cm⁻¹ at 25 °C) and high electrochemical stability (ESW = 5.9 V vs. Ag⁺/Ag and 3.7 V vs. Li⁺/Li).