|
The star-like liquid crystals, as new type of polymer liquid crystals materials, has a complete different molecular structure from that of tradition rodlike molecule, which behaves star shape structure: the oriented structure is completely symmetrical, synthesized by center atom(or aromatic ring)and liquid crystal that has liquid crystal property through esterification. The star-like liquid crystals not only has a similar nematic phase to the rod-like molecular but also has columnar phase from discotic liquid crystals. It connect the rod-like molecular and discotic liquid crystals as a bridge, and the core of liquid crystals dendrimers.In this paper, the study of star-like liquid crystals includes cross-disciplinary knowledge, which has important theory significance and potential application value. on the basis of consult lots of reports, by means of the synthesis of the different substituents bits, the phloroglucinol, pentaerythritol, anhydrous dextrose were choose as the center, and the star-like liquid crystals with three, four and five arms were obtained by esterification.The liquid crystal arms of the different terminal position substituent are as follows:6-(4-(4-nitrobenzoyloxy) phenoxy)-6-oxohexanoic acid,10-(4-(4-nitrobenzoyloxy) phenoxy)-10-oxohexanoic acid,6-(4-(4-ethoxybenzoyloxy) phenoxy)-6-oxohexanoic acid,10-(4-(4-ethoxybenzoyloxy) phenoxy)-10-oxodecanoic acid,6-(4-(4-chlorine benzoyloxy) phenoxy)-6-oxohexanoic acid,10-(4-(4-chlorine benzoyloxy) phenoxy)-10-oxohexanoic acid,6-(4-(benzoyloxy) phenoxy)-oxohexanoic acid, while no terminal position substituent or terminal position substituent with chlorine could not behave liquid crystal performance.The liquid crystal arms react with hydroxyhydroquinone, pentaerythritol, anhydrous dextrose via esterification could obtain multiple star-shaped liquid crystal compound, respectively. Afterwards, FT-IR,1H-NMR,DSC and POM were used to investigate their structure,performance and the effect of different terminal position substituent on the liquid crystalline properties. The results are as follows:(1)Liquid crystal arms M1and M2appeared liquid crystalline properties when lowering temperature; Liquid crystal arms M3and M4appeared liquid crystalline properties no matter when rising or lowering temperature, which is thermal induced bidirectional transition liquid crystalline; Liquid crystal arms M5, M6, M7did not appeare liquid crystalline properties no matter when rising or lowering temperature, so they are no liquid crystal performance.(2)The star-shaped liquid crystal compound synthetized by the the liquid crystal arms(M1, M2, M3and M4)with liquid crystal performance also behaves liquid crystal performance, while the Star-Shaped liquid crystal compound synthetized by the liquid crystal arms(M5, M6, M7)with no liquid crystal performance also behaves no liquid crystal performance. The star-shaped liquid crystal compound (P1, P3, P8, P9, P15and P16) appeared liquid crystal phase when lowering or increasing temperature, which is thermal induced bidirectional transition liquid crystalline. P2, P4, P7, P10, P13and P14are thermal induced uni-directional transition liquid crystalline, among which, only P4appeared liquid crystal phase when increasing temperature, while others appeared liquid crystal phase when lowering temperature.
|