Influence of Chain Rigidity and Dielectric Constant on the Glass Transition Temperature in Polymerized Ionic Liquids

Polymerized ionic liquids (PolyILs) are promising candidates for a wide range of technological applications due to their single ion conductivity and good mechanical properties. Tuning the glass transition temperature (T_g) in these materials constitutes a major strategy to improve room temperature conductivity while controlling their mechanical properties. In this paper, we show experimental and simulation results demonstrating that in these materials T_g does not follow a universal scaling behavior with the volume of the structural units V_m (including monomer and counterion). Instead, T_g is significantly influenced by the chain flexibility and polymer dielectric constant. We propose a simplified empirical model that includes the electrostatic interactions and chain flexibility to describe T_g in PolyILs. Finally, our model enables design of new functional PolyILs with the desired T_g.