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Vibrational Dynamics of a Chiral Smectic Liquid Crystal Undergoing Vitrification and Cold Crystallization
Crystals ( IF 2.7 ) Pub Date : 2020-07-30 , DOI: 10.3390/cryst10080655
Anna Drzewicz , Ewa Juszyńska-Gałązka , Wojciech Zając , Przemysław Kula

Vibrational dynamics in the glass transition and the cold crystallization process of (S)-4′-(1-methyloctyloxycarbonyl) biphenyl-4-yl 4-[7-(2,2,3,3,4,4,4-heptafluorobutoxy) heptyl-1-oxy]-benzoate (3F7HPhH7) was studied by Fourier transform infrared spectroscopy (FTIR) during cooling/heating experimental runs. The measured spectra processing was supported by quantum chemical density functional theory (DFT) calculations (frequency assignments). The perturbation-correlation moving window two-dimensional analysis (PCMW2D) was performed to examine how the height of individual absorption bands change under with temperature. Two-dimensional correlation analysis (2D-COS) was used to detect freezing-in or activation of the stochastic movements during the vitrification and the cold crystallization processes. Upon cooling, the vitrification process involves freezing-in of the stochastic movements of ester groups. Upon heating, as the cold crystallization process begins, the first to respond are the vibrations of the C–O–C and C=O groups in the rigid core.

中文翻译:

玻璃化和冷结晶过程中手性近晶液晶的振动动力学

(S)-4'-(1-甲基辛基氧羰基)联苯-4-基4- [7-(2,2,3,3,4,4,4,4-七氟丁氧基)的玻璃化转变和冷结晶过程中的振动动力学在冷却/加热实验过程中,通过傅立叶变换红外光谱(FTIR)研究了1-庚氧基]-苯甲酸庚酯(3F7HPhH7)。测得的光谱处理得到了量子化学密度泛函理论(DFT)计算(频率分配)的支持。进行了摄动-相关移动窗口二维分析(PCMW2D),以研究各个吸收带的高度如何随温度变化。二维相关分析(2D-COS)用于检测玻璃化和冷结晶过程中的随机运动的冻结或激活。冷却后 玻璃化过程包括冻结酯基团的随机运动。加热后,随着冷结晶过程的开始,首先做出反应的是刚性芯中C–OC和C = O组的振动。
更新日期:2020-07-30
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