通过收敛法合成了母核为亚胺键连接的芳环与氟代芳环,外围为3,4,5-三(正十二烷氧基)苯基亚甲基的第一代树枝状亚胺分子,并对其热致液晶行为和聚集体结构进行了研究.示差扫描量热和热台偏光光学显微镜研究表明该亚胺分子在93℃到118℃的温度范围内为具有双折射的液晶相.X-射线衍射结果表明该亚胺分子的液晶相为斜柱状结构(a=4.90 nm,b=3.51 nm,γ=110°).芳环-氟代芳环的面对面交替堆积和氢键驱动亚胺分子形成了柱状聚集体,分子外围的柔性十二烷氧基链的无序伸展,与母核聚集体发生微相分离,促使了亚胺分子斜柱状液晶相的形成.
Imine 1 with a phenylene and a tetrafluorophenylene units tethered by an imine bond was synthesized, and its self-assembly and thermotropic liquid crystalline behaviour were studied. Imine 1 showed a high thermal stability with only 5% mass loss occurred at 346℃ as revealed by thermal gravimetric analysis(TGA). The heating process of differential scanning calorimetry(DSC) analysis revealed two endothermic peaks at 93 and 118℃, which were attributed to the transition from the crystalline phase into the liquid crystalline phase and the transition from liquid crystalline phase into the isotropic phase, respectively. Meanwhile, similar phase transition behaviors were observed in the cooling process, with phase transition temperatures at 97 and 84 ℃, respectively. In addition, in the polarized optical microscopy(POM) analysis, imine 1 melt and turned birefringent at 110℃, then it transformed into an isotropic liquid at 118℃. Upon slowly cooling at a rate of 1 K/min, an occurrence of a liquid crystal birefringence was detected again at 106℃. Thus, the results obtained with POM agreed well with DSC thermograms, both characterizations indicated imine 1 formed liquid crystalline phase from 93℃ to 118℃. Wide-angle X-ray diffraction(WAXD) revealed an oblique columnar lattice of imine 1 in the liquid crystal state, with a = 4.90 nm, b = 3.51 nm and γ = 110°. Two-dimensional X-ray diffraction(2D XRD) patterns of oriented sample of imine 1 further confirmed its oblique columnar liquid crystalline phase. The results revealed that arene-perfluoroarene face-to-face stacking and amide-amide hydrogen bonding interactions were responsible for the formation of columnar aggregation of imine 1. Furthermore, disordered dodecyloxyl chains on both ends of the molecule were proposed to interpenetrate with one another, which formed microphase separation in the aggregation, and contributed to the formation of long-range ordered columnar liquid crystalline phase.