Phase Behavior and Dynamics of Binary and Multicomponent Thioester Liquid Crystal Mixtures

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• 作者：Arkadiusz RudzkiSławomir Zalewski ; Beata Suchodolska ; Jan Czerwiec ; Mirosława D. Ossowska-Chruściel ; Janusz Chruściel
• 刊名：Journal of Physical Chemistry B
• 出版年：2017
• 出版时间：January 12, 2017
• 年：2017
• 卷：121
• 期：1
• 页码：273-286
• 全文大小：909K
• ISSN：1520-5207

文摘

The results of studies conducted by means of complementary methods, differential scanning calorimetry, transmitted light intensity measurements, polarized optical microscopy, the electro-optical method, as well as dielectric relaxation spectroscopy of two new liquid crystal mixtures are presented. The first mixture is an equimolecular binary mixture consisting of two ferroelectric chiral liquid crystals from the homologous series, abbreviated as (S)-MHOBSn. The second mixture is a multicomponent mixture and consists of four mesogens from the homologous series of nOS5 as the base of the mixture, abbreviated as 610712 and chiral MHOBS8. The binary MHOBS4 + MHOBS7 mixture has an enantiotropic phase sequence, as follows: Cr, SmG*, SmI*, SmC*, N*. The second mixture has the same phase sequence but a much wider temperature range of ferroelectric SmC* phase. The switching time changes from 50 to 90 μs in the SmC* phase of the binary MHOBS4 + MHOBS7 mixture, whereas in 610712 + MHOBS8, the change is more than an order of magnitude higher, ranging from 500 to 3500 μs. Numerical analysis of the dielectric spectra results point toward the complex dynamics of the MHOBS4 + MHOBS7 and 610712 + MHOBS8 mixtures. The relaxation processes in the crystalline, SmC*, SmI*, and SmG* subphases have been observed and described. The relaxation processes have been detected up to 12 °C. There is a very low intensity Goldstone mode in SmC* and a low-frequency noncancellation mode in the SmI* and SmG* phases.