Ice nucleation and supercooling behavior of polymer aqueous solutions

We determined the homogeneous nucleation temperature depression, ΔT_f,hom, the equilibrium melting point depression, ΔT_m, and the value λ, which can be obtained from the linear relationship ΔT_f,hom = λΔT_m, for aqueous solutions of PEG (200-20,000 g mol⁻¹), PVP (10,000, 35,000, 40,000 g mol⁻¹), and dextran (10,000 g mol⁻¹) in the concentration range 0-40 wt% using the emulsion method. The molecular weight dependence of T_f,hom, T_m, and λ in PEG aqueous solutions was found to change in the vicinity of Mw 600-1540 at all concentrations. In addition, it was confirmed that for all of the polymers studied, there was a good linear relationship between λ and the logarithmic value of the self-diffusion coefficient D₀ of the solute molecule. These results indicate that the parameters that describe non-equilibrium freezing, such as T_f,hom and λ, are dependent on solution properties such as viscosity and self-diffusion of solute molecules.