Synthesis And Properties Of The Kind "H" Liquid Crystals

The tradition liquid crystal molecule most memorial is often rodlike or often bar-like. In recent years, some liquid crystal that the geometry characteristic are different from rodlike molecule have been designed and composed unceasingly by people. For instance, the molecule assumes flat type plate shape structure, the carbon atom on molecule one end or both ends has two long-chain swallow tail structure, star type structure, banana type structure substituting base etc. With the development of liquid crystal chemistry, mission designing that the compound composing architectural liquid crystal of new model already becomes the foundation that the liquid crystal molecule designs. Importing mesogenic units of new types into main-chain, composing various novel side-chain liquid crystalline polymers(LCPs), and analyzing their new and promising properties with respect to those of traditional linear polymers, are becoming front problems in the research field of LCPs. In this thesis, our recent results will be reported on composing of "H" type LCs.These research works expanded the types of the LCPs, provided some theoretical bases in design and synthesis of LCPs for some specific properties, and can also establish foundations for the application study of new types of LCPs.In this dissertation, we will report the design and synthesis of four compounds of "H" type LCs, tow monomers, two corresponding series of LCPs. Four compounds of "H" type LCs are bis(4-(4-ethoxybenzoyloxy)phenyl)2,3-bis(4-(allyloxy) benzoyloxy)succinate(M1), bis(4-(4-ethoxybenzoyloxy)phenyl)2,3-bis(4-(undec-10-enoyloxy)benzoyloxy)succinate(M2), bis(4-(4-(allyloxy)benzoyloxy)phenyl)2,3-diacetoxysuccinate(M3), diethyl-2,3-bis(4-(4-(ally-loxy)benzoyloxy)benzoyloxy)succinate(M4). Two monomers are 4-(4-nitrobenzoyloxy)phenyl 4-(undec-10-enoyloxy)benzoate(M5),4-(4-(undec-10-enoyloxy)benzoyloxy)cholestery benz-oate(M6). And they are carried on the stem grafting copolymerization with the siloxanes.The structures and properties of the obtained star-shaped LCs, liquid crystalline monomers, and LCPs are investigated by FT-IR spectroscopy,1H-NMR spectroscopy, differential scanning calorimetry (DSC), polarizing optical microscopy (POM). Their structure-property relationships are discussed in detail. All the monomers(M1-M6) are liquid crystals. M1-M3 are thermal enantiotropic nematic liquid crystals, and exhibited droplet textures and marble texture on heating process, droplet textures and schlieren textures on cooling cycle; M4 is thermal unilateral nematic liquid crystals, and exhibited droplet textures and schlieren textures on heating process; M5 is thermal enantiotropic smectic liquid crystals, and exhibited smectic fan-shaped texture and focal-conic texture on heating process, focal-conic texture on cooling cycle; M6 is thermal unilateral cholesteric liquid crystal, oily-streak texture on heating process.Polymers P1 and P2 are thermal enantiotropic liquid crystals. With increasing the content of the compound of "H" type LC in the elastomers, the Tm and Ti of the tow polymer series are all increased. But in the polymers P1 series, when content of the compound of "H" type LC(M1) increased between 15mol% and 20mol%, Ti decreased to 203.7℃and 204.9℃,ΔT of the copolymers decrease mostly. For the polymers P2 series, when content of the compound of "H" type LC(M2) increased between 9mol% and 15mol%, Ti decreased to 228.2℃and 217.1℃,ΔT of the copolymers decrease mostly.