Freezing of polymer solutions has been extensively investigated from many aspects, especially the complex pattern formation. The cellular/dendritic microstructures occurred in freezing of polymer solutions are usually believed to belong to the type of diffusion-induced Mullins–Sekerka (M − S) instability. However, the presence of macromolecule as an impurity in water is significantly different from that of small ions. The quantitative investigation on transient process of directional freezing of polymer solutions remains lack due to some challenges. For the first time, we in-situ observed the planar instability behaviors during unidirectional freezing of a polymer solution together with a typical ionic solution with manipulated ice orientation. It is found that unlike the ionic solution exhibiting typical diffusion-controlled planar instability, the solute recoil of a polymer solution deviated severely from the predictions of Warren-Langer (W-L) model. Meanwhile, the real-time observation shows that the polymer solution exhibits a global instability mode instead of a local instability mode. These results reveal the complex physics behind freezing of a polymer solution, and are believed to promote relevant investigations in terms of the theoretical approach to describing the freezing behavior of a polymer solution.

聚合物溶液的冷冻已从许多方面进行了广泛研究，尤其是复杂图案的形成。通常认为冻结在聚合物溶液中的细胞/树突状微观结构属于扩散引起的Mullins-Sekerka（MS）不稳定性的类型。但是，大分子作为水的杂质的存在与小离子的存在显着不同。由于一些挑战，仍然缺乏对聚合物溶液定向冻结的瞬态过程的定量研究。第一次，我们在原位观察了聚合物溶液与典型的离子溶液（具有受控的冰取向）一起单向冻结期间的平面不稳定性行为。发现与离子溶液不同，离子溶液表现出典型的扩散控制的平面不稳定性，聚合物溶液的溶质后坐力严重偏离Warren-Langer（WL）模型的预测。同时，实时观察表明聚合物溶液表现出整体不稳定模式而不是局部不稳定模式。这些结果揭示了聚合物溶液冷冻背后的复杂物理现象，并且据信将在描述聚合物溶液冷冻行为的理论方法方面促进相关研究。