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A series of supramolecular liquid crystals, named mOOBA-HOBA (m, which is the molar ratio of OOBA to HOBA) were successfully synthesized via mixing different molar ratio of 4-Octyldecyloxybenzoic acid (OOBA) and 4-hexadecyloxy benzoic acid (HOBA). The chemical and phase structures were investigated by the combination of techniques, including FT-IR, DSC, X-ray and POM. The experimental results revealed that the LC phase structures of the original symmetrical dimmers in OOBA and HOBA were both dissociated while a new asymmetrical dimmer was formed between OOBA with HOBA through hydrogen bonding in the binary mixture. DSC results show that the phase transition for entering into LC phase shifts to lower temperature, and the nematic-isotropic phase transition also shifts to lower temperature. These different phase transition behaviors should be ascribed to the asymmetrical dimmers between OOBA with HOBA. POM demonstrated that these OOBA-HOBA binary mixtures tend to show a lower liquid crystalline phase temperature and broad temperature range.

Liquid crystal (LC) is a kind of special state between the solid and the liquid, and has both the fluidity of liquid and crystal anisotropy of the solid. These two features make the LC more active under the electrical, magnetic, and temperature field and micro flow which can be controlled precisely can be induced. This makes it possible that the LC can be used as the media for micro-fluidic driving and control field. In order to explore the characteristics and formation mechanism, and the overall features of the liquid crystalline micro-flows, a Micro-PIV system special for measuring the liquid crystalline micro flow was set up in this study. Besides, we did the experiments to measure the LC micro flow induced by the electric field and the temperature field with this system, and got more satisfactory results.

To improve temperature-sensitivity of conventional poly(N-isopropylacrylamide) (PNIPAM) hydrogel, a kind of lyotropic liquid crystal based on polyoxyethylene 20 cetyl ether (Brij 58, C16E20) was used as template to prepare nanostructured hydrogel. The structure, morphology swelling behavior and temperature-sensitivity of confined PNIPAM hydrogel were characterized. SEM images showed that polymerization of N-isopropylacrylamide (NIPAM) in Brij 58 solution formed hydrogel with honeycomb structure. Compared to pure PNIPAM hydrogel, the swelling rate increases. The time for losing water was greatly shortened. The thermal-responsibility measured by differential scanning calorimeters (DSC) was improved remarkably. Finally, as for oscillatory swelling/deswelling behaviors, rapid recovering could be found by alternating temperature from 20 to 37°C.