Thermophysical properties of glycerol and polyethylene glycol (PEG 600) based DES

In this study, the Deep Eutectic Solvent (DES) is prepared based on glycerol and polyethylene glycol 600 (PEG) as hydrogen bond donor and choline chloride (ChCl) as hydrogen bond acceptor. The glycerol based DESs were formed with ratio of 1:2, 1:3, 1:4 and 1:5 whereas three-component DESs of ChCl, PEG and glycerol were synthesized with ratio 1:3:2, 1:4:2 and 1:5:2. The DESs were subjected to DSC, Karl Fishcer, thermal conductivity, viscosity and density testing. The melting temperature (Tm) for PEG based DESs were found to in the region of 18 °C. The moisture content in DESs were identified through Karl Fishcer testing was found to be < 1% which is desired when synthesizing a DES. The thermal conductivity of glycerol based DESs decreases with respect to pure glycerol whereas for PEG based DESs shows positive enhancement of thermal conductivity at temperatures below 60 °C. The viscosity of glycerol DESs decreases with increasing temperature and the value of PEG DESs' viscosities was found to be higher than the pure PEG. All the DES samples have linear decrease across a temperature range with highest density achieved at 1.2155 g/cm3 with temperature of 25 °C for molar ratio of ChCl to glycerol of 1:4 (DES 4).