Prefreezing is a first-order equilibrium phase transition at the melt–solid interface that results in an abrupt formation of a nanoscopic crystalline layer at the interface above the bulk melting temperature. A recently developed phenomenological theory predicts that the prefreezing transition temperature T_max depends primarily on the difference of the interfacial free energies γ_sub,melt – (γ_sub,cry + γ_cry,melt), whereas the minimum jump of thickness at T_max or minimum order parameter l_min depends on the ratio . As such, T_max and l_min can vary independently. To test these predictions, we present in situ atomic force microscopy measurements of poly(ϵ-caprolactone) (PCL) prefrozen on a MoS₂ substrate and compare the results with those of our previous study of PCL prefrozen on graphite as well as polyethylene prefrozen on the same two substrates. The experiments show that T_max of the prefrozen PCL on MoS₂ remains nearly the same as on graphite, whereas l_min clearly decreases, thereby indicating that T_max and l_min are indeed independent of each other. The quantitative analysis of these experimental findings is consistent with the theory. With these results, we conclude a first series of experiments aimed at an experimental exploration of the theoretically predicted variations of the prefreezing phenomenon.

中文翻译：

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预冻结转变时转变温度和预冻层厚度的独立变化

预冻结是熔体-固相界面的一阶平衡相变，会导致在整体熔融温度以上的界面突然形成纳米级晶体层。最近发展的现象学理论预测，预冻结转变温度T _max主要取决于界面自由能γsub _，melt –（γsub _，cry +γcry _，melt）的差，而厚度在T _max或最小阶数参数l _min取决于比率。因此，T _max和l _min可以独立变化。为了检验这些预测，我们提出了在MoS ₂基底上对聚（ε-己内酯）（PCL）预冻的原位原子力显微镜测量，并将结果与​​我们先前对石墨上的PCL预冻和在聚乙烯上的聚乙烯预冻的研究结果进行了比较。相同的两个基板。实验表明，在MoS ₂上预冷冻的PCL的T _max保持与在石墨上几乎相同，而l _min明显降低，从而表明T _max和l _min确实彼此独立。这些实验结果的定量分析与理论相符。有了这些结果，我们得出了第一批实验，旨在对理论上预测的预冻结现象的变化进行实验探索。