Poly(ethylene glycol) diacrylate as a novel chaotropic compound for design of aqueous biphasic systems

In this work novel solvent, poly(ethylene glycol) diacrylate (PEGDA) of average number molecular weight 700, is proposed for design of aqueous biphasic systems with salting-out agents: K3PO4/Na3C6H5O7/K2CO3/MnSO4/Li2SO4/ZnSO4. Ternary liquid-liquid equilibrium experiments were conducted at constant temperature 298.15 K and 0.1 MPa, where binodal curves and tie-lines were determined. The consistency of equilibrium data were checked and confirmed using Othmer-Tobias and Bancroft equations. Density ρ, viscosity η and refractive index nD have been experimentally measured for PEGDA 700 + water system over the temperature range T = (293.15 to 323.15) K with temperature step 5 K and at atmospheric pressure. Excess molar volumes VE, viscosity deviations Δη, deviations in refractive index ΔnD, excess Gibbs free energy of activation of viscous flow ∆G⁎E, partial molar volumes V¯i, excess partial molar volumes V¯iE and it's values at infinite dilutions V¯iE,∞ were calculated from experimental data and used to analyze non-ideal behavior of polymer aqueous solution. Fourier-transform infrared analysis (FT-IR) of PEGDA + water mixture and corresponding pure components was performed at T = 298.15 K in order to gain insight into the molecular structure of the mixture. FT-IR analysis indicates the absence of hydrogen bonding between PEGDA 700 and water. This leads to the conclusion that non-ideal behavior of mixture is contributed to geometrical packing or van der Waals forces of different species.