Comparing Ammonium and Phosphonium Polymerized Ionic Liquids: Thermal Analysis, Conductivity, and Morphology

Conventional free radical polymerization and anion metathesis of ammonium and phosphonium styrenics successfully generates high‐molecular‐weight polymerized ionic liquids (PILs). Phosphonium polyelectrolytes containing Cl ‐ counterions display significantly higher thermal stabilities (>370 °C) compared with ammonium analogs (<220 °C). Anion exchange to BF 4 – , TfO – , and Tf 2 N – improves the thermal stability of all the PILs and depresses their T g . Impedance‐spectroscopy‐probed ionic conductivities of PILs containing Tf 2 N – , and phosphonium PILs exhibit higher values than ammonium analogs. Phosphonium PILs displayed many advantages over ammonium PILs for emerging applications that demand higher thermal stabilities and ionic conductivities.