Deptuch Aleksandra, Drzewicz Anna, Urbańska Magdalena, Juszyńska-Gałązka Ewa
Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, PL-31342 Kraków, Poland.
Institute of Chemistry, Military University of Technology, Kaliskiego 2, PL-00908 Warsaw, Poland.
Materials (Basel). 2025 Jun 29;18(13):3085. doi: 10.3390/ma18133085.
Three liquid crystalline mixtures were investigated, consisting of compounds abbreviated as MHPOBC and 3F5FPhF6 with molar ratios 0.9:0.1 (MIX5FF6-1), 0.75:0.25 (MIX5FF6-2), and 0.5:0.5 (MIX5FF6-3). The presence of the smectic A*, smectic C*, and smectic C* phases was observed in all mixtures. The hexatic smectic X* phase, present in pure MHPOBC, disappeared quickly with an increasing admixture of 3F5FPhF6. Vitrification of smectic C* was observed for the equimolar mixture, with the glass transition temperature and fragility index comparable to the pure glassforming 3F5FPhF6 component. Partial crystallization to conformationally or orientationally disordered crystal phases was observed on cooling in two mixtures with a smaller fraction of 3F5FPhF6. Broadband dielectric spectroscopy was applied to study the relaxation times in smectic and crystal phases. Vogel-Fulcher-Tammann, Mauro-Yue-Ellison-Gupta-Allan, and critical-like models were applied for analysis of the α-relaxation time in supercooled smectic X* and smectic C* phases.
研究了三种液晶混合物，它们由简称为MHPOBC和3F5FPhF6的化合物组成，摩尔比分别为0.9:0.1（MIX5FF6 - 1）、0.75:0.25（MIX5FF6 - 2）和0.5:0.5（MIX5FF6 - 3）。在所有混合物中均观察到近晶A相、近晶C相和近晶C相的存在。纯MHPOBC中存在的六方近晶X相随着3F5FPhF6混合物比例的增加而迅速消失。对于等摩尔混合物，观察到近晶C的玻璃化现象，其玻璃化转变温度和脆性指数与纯玻璃形成成分3F5FPhF6相当。在冷却含有较小比例3F5FPhF6的两种混合物时，观察到部分结晶为构象或取向无序的晶相。应用宽带介电谱研究近晶相和晶相中的弛豫时间。Vogel - Fulcher - Tammann、Mauro - Yue - Ellison - Gupta - Allan和类临界模型被用于分析过冷近晶X相和近晶C*相中的α弛豫时间。
