Kimizuka Norihito, Viriyarattanasak Chotika, Suzuki Toru
Department of Food Science and Technology, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo 108-8477, Japan.
Cryobiology. 2008 Feb;56(1):80-7. doi: 10.1016/j.cryobiol.2007.10.179. Epub 2007 Nov 19.
We determined the homogeneous nucleation temperature depression, DeltaT(f,hom), the equilibrium melting point depression, DeltaT(m), and the value lambda, which can be obtained from the linear relationship DeltaT(f,hom)=lambdaDeltaT(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 lambda 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 lambda and the logarithmic value of the self-diffusion coefficient D(0) of the solute molecule. These results indicate that the parameters that describe non-equilibrium freezing, such as T(f,hom) and lambda, are dependent on solution properties such as viscosity and self-diffusion of solute molecules.
我们使用乳液法测定了聚乙二醇（200 - 20,000 g mol⁻¹）、聚乙烯吡咯烷酮（10,000、35,000、40,000 g mol⁻¹）和葡聚糖（10,000 g mol⁻¹）在浓度范围为0 - 40 wt%的水溶液的均相成核温度降低量ΔT(f,hom)、平衡熔点降低量ΔT(m)以及可从线性关系ΔT(f,hom)=λΔT(m)得到的λ值。发现在所有浓度下，聚乙二醇水溶液中T(f,hom)、T(m)和λ对分子量的依赖性在Mw 600 - 1540附近发生变化。此外，已证实对于所有研究的聚合物，λ与溶质分子的自扩散系数D(0)的对数值之间存在良好的线性关系。这些结果表明，描述非平衡冻结的参数，如T(f,hom)和λ，取决于溶液性质，如溶质分子的粘度和自扩散。
