Ice nucleation and supercooling behavior of polymer aqueous solutions

We determined the homogeneous nucleation temperature depression, ΔTf,hom, the equilibrium melting point depression, ΔTm, and the value λ, which can be obtained from the linear relationship ΔTf,hom = λΔTm, 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 Tf,hom, Tm, 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 Tf,hom and λ, are dependent on solution properties such as viscosity and self-diffusion of solute molecules.