Interface-Induced Crystallization of Polycaprolactone on Graphite via First-Order Prewetting of the Crystalline Phase
Interface-Induced Crystallization of Polycaprolactone on Graphite via First-Order Prewetting of the Crystalline Phase
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DOI：
10.1021/acs.macromol.7b02113
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发表时间：
2018-01-09
期刊：
影响因子：
5.5
通讯作者：
Thurn-Albrecht, Thomas
中科院分区：
文献类型：
--
作者：
Flieger, Ann-Kristin;Schulz, Martha;Thurn-Albrecht, Thomas
固体基质上的液体的界面诱导结晶可以通过异相成核或通过预冷冻发生，即，形成晶体层，该晶体层在高于本体熔化温度时已经稳定。在冷却时，该层充当“理想晶核”。使用原位AFM测量，我们在这里表明，聚己内酯表现出在石墨上的预冻结。由于液相的特殊润湿行为，这是不同于以前研究的系统聚乙烯在石墨上，它是可能的，直接测量作为温度的函数的预冻层的厚度。形成具有有限厚度的薄结晶层，其在接近相变液体固体时增加并理论上发散。实验结果表明，预冻是一级相变。
Interface-induced crystallization of a liquid on a solid substrate can occur either via heterogeneous nucleation or via prefreezing, i.e., the formation of a crystalline layer, which is stable already above the bulk melting temperature. Upon cooling this layer acts as an "ideal crystal nucleus". Using in situ AFM measurements, we here show that polycaprolactone exhibits prefreezing on graphite. Because of the special wetting behavior of the liquid phase, which is different from the previously investigated system polyethylene on graphite, it is possible to directly measure the thickness of the prefrozen layer as a function of temperature. A thin crystalline layer forms with a finite thickness which increases and theoretically diverges upon approaching the phase transition liquid solid. The results of our experiments show that prefreezing is a first-order transition.