First consideration of density scaling of the dynamic and thermodynamic properties in polymerized ionic liquid.

The density scaling idea is a general feature of glass-forming materials, e.g., van der Waals liquids and polymer melts. According to this concept, the data of dynamic properties collected in isobars and isotherms collapse to a single curve when expressed versus TV^γ, where T is temperature, V is specific volume, and γ is scaling exponent being a material constant independent of thermodynamic conditions.
Herein, we test, for the first time, the scaling concept of dynamic and thermodynamic properties for polymerized ionic liquid (PIL). Since, various types of interactions can exist in ionic materials (balance between Coulomb interactions, van der Waals forces, and hydrogen bonds), and one of the ions is structurally constrained as part of the polymer skeleton, the validity of scaling concept is not obvious. We find experimentally that density scaling of ionic conductivity does not work. Additionally, concerning scaling of the entropy, a master curve can be obtained by taking the scaling exponent to be a linear function of total entropy.