四氢吡咯烷离子液体液晶研究

Study on ionic liquid crystalline of tetrahedron pyrrolidinium

合成了亲水性和疏水性的饱和杂环类离子液体N-十六烷基-N-甲基四氢吡咯烷溴化物与四氟合硼酸盐,采用偏光显微镜、变温X射线衍射仪和热化学等方法,研究两类离子液体液晶结构、自组装过程和相转变等特性,研究负离子对饱和杂环类离子液体自组装行为的影响.结果发现,该两种离子液体均可在熔点以上形成层状液晶,负离子结构与大小对离子液体液晶的结构与性质具有非常重要的影响,BF4-比Br-体积大,使吡咯烷环和环上的长碳链以较大的间隔排列,形成分子在近晶平面层内有序分布,结构非常接近固态的近晶型液晶.

Hydrophilic and hydrophobie ionic liquid crystals, N-methyl-N-hexadecyl tetrahedron pyrrolidinium bromide and tetrafluoroborate were synthesized. The liquid crystal structure, self-assembly process and phase transition were studied by polarizing optical microscope, temperature-dependent wide X-ray diffraction, thermal gravity analysis and differential scanning calorimetry. Results showed that the two ionic liquids exhibit thermotropic liquid crystalline. In comparison with bromide, liquid crystalline of tetrafluoroborate exhibited lower onset temperature of the smectic phase decreasing to 51.4 ℃ and more regular molecule assembly which was very close to the solid state. The reason is due to the larger size of anion which affording larger space for the long carbon lines to assemble in a more regular style. At the same time, the larger space between the IL molecules led to weaker molecular interaction, resulting in a lower temperature range of liquid crystalline. It demonstrates that the structure and symmetry of anion play important roles in the structure and properties of liquid crystalline.