Synthesis And Properties Of Star-Shaped Liquid Crystals And Side-Chain Liquid Crystalline Polymers Containing Bioactive Group

The research on liquid crystals has been done for many years. Due to the unique optical, electromagnetical, mechanical properties and chemical stability, liquid crystals are used in many fields such as optics, message, military, print, and composite materials. Presently, the design and synthesis of new liquid crystals became hot spots of research with the development of liquid crystals synthesis. In recent years, some bioactive nature compounds were successfully used to design and synthesis of novel liquid crystals. In this thesis, our recent results will be reported on synthesis and properties of novel star-shaped liquid crystals and side-chain liquid crystalline polymers containing bioactive group. These research works expanded the types of the liquid crystals, provided some experimental data in design and synthesis of the novel liquid crystals for some specific properties.In this dissertation, we will report the design and synthesis of two series of star-shaped liquid crystals, three series of liquid crystalline monomers, and four corresponding series of liquid crystalline polymers. The two series of star-shaped liquid crystals are GGnGC (n=2,4,6) series containing glutamic acid residue, GCnDB (n=0,4,8) series containing chenodeoxycholic acid residue. The three series of liquid crystalline monomers are 24-[4'-hydroxybiphenyl-4-yl-4-(allylox-y)benzoyloxy]-3α,7a-di{m-[4'-(4-ethoxybenzoyloxy)biphenyl-4-yloxy]-m-oxoalk-anoyloxy}-5β-cholane series M-n (n=0,4,8), L-r-{n-[4-(cholesterylcarbonyl)b-enzoyloxy]alkoxy}glutamic acid series M1-n(n=2,4,6),and L-r-{n-[4-((4'-(all-yloxy)biphenyl-4-yloxy)carbonyl)benzoyloxy]alkoxy}glutamic acid series M2-n (n =2,4,6). The side-chain polymers P-n (n=0,4,8) series are synthesized by radicalpolymerization, and other three series of polypeptide side-chain polymers are synthesized by N-carboxyanhydride (NCA) method, they are homopolymer P1-n(n=2,4,6) series, homopolymer P2-n(n=2,4,6) series, and copolymer P3 series. To our knowledge, the obtained compounds, monomers, and polymers have never been reported up to now, they are innovative.The structures and properties of liquid crystals and side-chain liquid crystalline-polymers are confirmed by fourier transform infrared, NMR spectra, differential scanning calorimetry, thermogravimetric analyse, polarizing optical microscopy, specific rotation, and X-ray diffraction. The results list below:1. Two series of novel star-shaped liquid crystals are synthesized. They use glucose as the chiral core structure, and mesogenic units containing chenodiol moieties or glutamic acid moieties are introduced to the five hydroxy groups of glucose by direct esterfication. Two series of novel star-shaped compounds are enantiotropic thermotropic liquid crystals. The study also shows that the formations of star-shaped liquid crystals and'their properties are directly affected by the phase types of mesogenic units and length of flexible spacer(1) The star-shaped liquid crystalline GGnGC(n=2,4,6) series containing glutamic acid moieties demonstrate wide mesophase temperature range and high thermal stability. These compounds have not sharp DSC endotherm peak of melting-point. The.melting point, clear point, and mesophase temperature range of GGnGC series decrease with the flexible spacer length of GGwGC.series extends. The SROT of GGhGC series increases with the flexible spacer lergth of GGnGC series extends, but the flexible spacer length does not affect-mesogenic type and texture of GGnGC series. The oil-thread and focal-conic textures are observed, which are typical characteristic of cholesteric liquid crystalline phase.(2) The star-shaped liquid crystalline GCnDB (n=0,4,8) series containing' chenodiol. moieties demonstrate wide mesophase temperature range and high thermal stability. These compounds have not sharp DSC endotherm peak of melting point. The melting point of GCnDB series decreases with the flexible spacer length of GCnDB series extends, and the mesophase temperature range of GCnDB series increases with the flexible spacer length of GCnDB series extends. The SROT of GCnDB series increases with the flexible spacer length of GCnDB series extends, but the flexible spacer length does not affect mesogenic type and texture of GGnGC series. The schlieren and threaded textures are observed, which are typical characteristic of nematic liquid crystalline phase.2. The liquid crystalline monomer 24-[4'-hydroxybiphenyl-4-yl-4-(allylo-xy)benzoyloxy]-3a,7a-di{m-[4'-(4-ethoxybenzoyloxy)biphenyl-4-yloxy]-m-oxoal-kanoyloxy}-5β-cholae M-n (n=0,4,8) series are new type of Y-shaped liquid crystals, and they are enantiotropic nematic liquid crystals, the monomer L-r-{n-[4-(cholesterylcarbonyl)benzoyloxy]alkoxy}glutamic acid M1-n (n=2,4, 6) series are enantiotropic cholesteric liquid crystals, and monomer L-r-{n-[4-((4'-(allyloxy)biphenyl-4-yloxy)carbonyl)benzoyloxy]alkoxy}glutamic acid M2-n (n=2,4,6) series are enantiotropic nematic liquid crystals, both M1-n series and M2-n series are glutamic acid derivative liquid crystalline monomer. The influence of flexible spacer length of the three series of monomers on the phase-transition temperatures and mesophase temperature range respectively is great, but the flexible spacer length does not affect mesogenic type and texture of monomers.3. The four series of novel side-chain liquid crystalline polymers are enantiotropic thermotropic. The P-n series, P1-n series, and P-n series are homopolymer, and P3 series are copolymer. These polymers demonstrate wide mesophase temperature range and high thermal stability. The P-n series are enantiotropic nematic liquid crystalline phase; the P1-n series are enantiotropic cholesteric 1 iquid crystalline phase; the P2-n s eries are enantiotropic nematic liquid crystalline phase; the P3 series are enantiotropic nematic liquid crystalline phase. The influence of flexible spacer length of the three series of homopolymers on the phase-transition temperatures, mesophase temperature range, and SROT respectively is great, but the flexible spacer length does not affect mesogenic type and texture of homopolymers. The influence of the content of monomer L-r-{4-[4-(cholesterylcarbonyl)benzoyloxy]butoxy}glutamic acid (M1-4) on the phase-transition temperatures and mesophase temperature range of the copolymers is great, but the content of monomer M1-4 does not affect mesogenic type and texture of copolymers.