Wojnarowska Zaneta, Paluch Marian
August Chełkowski Institute of Physics, Silesian Center for Education and Interdisciplinary Research, University of Silesia in Katowice, 75 Pulku Piechoty 1a, 41-500 Chorzow, Poland.
J Phys Chem Lett. 2021 Dec 16;12(49):11779-11783. doi: 10.1021/acs.jpclett.1c03572. Epub 2021 Dec 2.
Nonequilibrium processes, including physical aging, belong to the most challenging phenomena of glassy dynamics. One of the fundamental problems that needs clarification is the effect of material polarity on the time scale of the structural recovery of glass. The importance of this issue arises from practical applications and recent findings suggesting a substantial contribution of dipole-dipole interactions to the dielectric permittivity spectra of polar glass-formers. Herein, we use dielectric spectroscopy to investigate structural relaxation and aging dynamics of highly polar glass-former 4-[(4,4,5,5,5-pentafluoropentoxy)methyl]-1,3-dioxolan-2-one (FPC), a derivative of propylene carbonate with ε = 180 and μ = 5.1. We show that ε″() data of FPC at < reveal complex behavior resulting from considerable cross-correlation effects. Namely, two characteristic aging time scales, reflecting the evolution of cross-correlation mode and generic structural relaxation toward equilibrium, are obtained at a given . Furthermore, a single stretched exponential behavior of ε″() has been received for weakly polar carvedilol with negligible dipole-dipole interactions.
包括物理老化在内的非平衡过程属于玻璃态动力学中最具挑战性的现象。一个需要阐明的基本问题是材料极性对玻璃结构恢复时间尺度的影响。这个问题的重要性源于实际应用以及最近的研究结果，这些结果表明偶极 - 偶极相互作用对极性玻璃形成体的介电常数谱有重大贡献。在此，我们使用介电谱来研究高极性玻璃形成体4 - [(4,4,5,5,5 - 五氟戊氧基)甲基] - 1,3 - 二氧戊环 - 2 - 酮（FPC）的结构弛豫和老化动力学，FPC是碳酸亚丙酯的衍生物，其ε = 180且μ = 5.1。我们表明，在低频下FPC的ε″(ω)数据呈现出由显著的交叉相关效应导致的复杂行为。具体而言，在给定频率下获得了两个特征老化时间尺度，它们反映了交叉相关模式的演变以及向平衡态的一般结构弛豫。此外，对于偶极 - 偶极相互作用可忽略不计的弱极性卡维地洛，ε″(ω)呈现出单一的拉伸指数行为。
