3.3.3. DSC Analysis

A Differential Scanning Calorimeter (DSC) 1 Star system (Mettler Toledo, Columbus, OH, USA) was used to investigate the phase transition of the PILs. The reproducibility for DSC is ± 0.2K with <1% based on indium calibration. In total, 10 mg of samples were sealed in aluminum pans and subject to analysis in a temperature range of 50–150 ◦C with a heating rate of 10 ◦C·min<sup>−</sup>1. The phase transition data were analyzed by using the second heating plot.

#### 3.3.4. Density (*p*) and Viscosity (*η*) Measurement

An Anton Paar Stabinger Viscometer (Graz, Austria) was used to simultaneously measure the density and viscosity of the PILs in a temperature range of 293.15–363.15 K with a temperature measurement accuracy of 0.02 K. The reproducibility of the density and viscosity measurements were ±5.10−<sup>4</sup> g.cm−<sup>3</sup> and 0.35%, respectively. The measurements were repeated several times and the average value was considered for further analysis. Prior to the density and viscosity measurements, the equipment was calibrated using a standard fluid provided by the supplier. A commercial imidazolium IL with known density and viscosity values was also used to validate the equipment.
