Visualization of Nonequilibrium Properties of a Crystalline Polymer: Formation of Ring-Lite Due to the Gibbs?Thomson Effect and Dark-Ring Due to the Melting Point Inversion
Visualization of Nonequilibrium Properties of a Crystalline Polymer: Formation of Ring-Lite Due to the Gibbs?Thomson Effect and Dark-Ring Due to the Melting Point Inversion
复制标题
结晶聚合物非平衡性质的可视化：由于吉布斯·汤姆逊效应而形成轻环，由于熔点反转而形成暗环
DOI：
10.1021/acs.cgd.1c01069
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发表时间：
2021
影响因子：
3.8
通讯作者：
Ohshima Masahiro
中科院分区：
文献类型：
--
作者：
Nishida Koji;Hikima Yuta;Koga Tsuyoshi;Ohshima Masahiro
通过结合聚合物材料的非平衡性质和快速温度跳跃技术，获得了具有环状形貌的聚合物微晶。在这里被称为“环片”，它由单组分聚合物的同心排列的结晶和熔融区域组成。在球晶的生长过程中，晶化温度Tc在一定的时间间隔内依次在低温和高温之间变化。这样，双峰熔融温度Tm由于吉布斯-汤姆逊效应交替印记内相同的球晶。随后，快速加热样品，使得仅具有较高Tm的区域保持在结晶状态。重要的是，熔点的反转也在显微镜下可视化为“暗环”。与由于“正常”吉布斯-汤姆逊效应而出现的环晶相反，我们发现，特定的加热速率使最初具有较低Tm的区域保持在结晶状态，而最初具有较高Tm的区域熔融，即，显示熔点的反转。通过快速扫描芯片量热法（FSC）的加热速率变化测量证实了熔点反转的发生。
A polymer crystallite having a ring-like morphology was obtained by combining the nonequilibrium nature of a polymeric material and a rapid temperature-jump technique. Termed “ring-lite” here, it consists of the concentrically arranged crystalline and molten regions of a single-component polymer. During the growing process of a spherulite, crystallization temperatureTcwas, in turn, changed between low and high temperatures at certain intervals. In this way, bimodal melting temperaturesTmdue to the Gibbs–Thomson effect were alternately imprinted within an identical spherulite. Subsequently, the sample was heated so rapidly that only the region having higherTmremained in a crystalline state. Importantly, inversion of the melting point was also microscopically visualized as a “dark-ring”. Contrary to the appearance of ring-lites due to the “normal” Gibbs–Thomson effect, we found that a specific heating rate caused the region having originally a lowerTmto remain in a crystalline state and that with originally a higherTmto melt, i.e., display inversion of the melting point. The occurrence of the melting point inversion was confirmed by heating rate variation measurements of fast-scan chip calorimetry (FSC).