| So far people have designed and synthesized a large number of traditional liquid crystal compounds like bar whose molecular structure is slender and2,3rings constitute molecule nuclear. Between ring and ring are connected directly or through a central group, and the two ends of moleculars. With the development of liquid crystal chemistry, design and synthesis of the new structure liquid crystal compounds have become the fundamental task of molecule design. In recent years, some liquid crystal compounds with geometric features distinctly different from bar molecules such as swallow-tailed, star-shaped, banana-shaped have emerged. Presently the design and synthesis of these new liquid crystals are hot spots of research. In this thesis, our recent results will be reported on composing of swallow-tailed liquid crystals, the importing of swallow-tailed mesogenic units and bar molecules mesogenic units into flexibe polysiloxane main-chain, and preparation of new types of side-chain liquid crystals. These research works expanded the types of the liquid crystals, provided some theoretical bases in design and synthesis of liquid crystals for some specific properties, and can also establish foundations for the application study of new types of liquid crystals.In this dissertation, we will report the design and synthesis of seven compounds of aromatic ester swallow-tailed compounds, three monomers, and three corresponding series of liquid crystalline polymers. The seven compounds of swallow-tailed compounds are4-[(3,5-diacetoxy)benzoyloxy]-4’-[(p-allyloxy)benzoyloxy]-biphenyl(Mi),4-[(3,5-bisbuyrylo-xy)benzoyloxy]-4’-[(p-allyloxy)benzoyloxy]-biphenyl(M2),4-[(3,5-bishexanoyloxy)benzoylo-xy]-4’-[(p-allyloxy)benzoyloxy]-biphenyl(M3),4-[(3,5-bisoctanoyloxy)benzoyloxy]-4’-[(p-al-lyloxy)benzoyloxy]-biphenyl(M4),4-[(3,4,5-trihexanoyloxy)benzoyloxy]-4’-[(p-allyloxy)-be-nzoyloxy]-biphenyl(M5),4-[(3,4,5-triacetoxy)benzoyloxy]-4’-[(p-allyloxy)-benzoyloxy]-biph-nyl(M6) and4-[(3,5-diacetoxy)benzoyloxy]-4’-[(p-allyloxy)benzoyloxy]-phenyl(M7). The three monomers are4-[(p-acetoxy)benzoyloxy]-4’-[(p-allyloxy)benzoyloxy]-phenyl(M8),4-[(p-nitryl)benzoyloxy]-4’-[(p-allyloxy)benzoyloxy]-phenyl(M9) and cholesteryl2-(4-(allyl-oxy)benzoyloxy)propanoic(Mio). By grafting copolymerization of monomers(M1and M10),(Mi and M8),(M5and M10) to the main chain of poly(hydrogenmethylsiloxane), three series of side-chain liquid crystalline polymers P1～P3are synthesized. To our knowledge, the obtained monomers and the polymers have never been reported up to now.The structures and properties of the obtained swallow-tailed liquid crystals, liquid crystalline monomers, and side-chain liquid crystalline polymers are investigated by FT-IR spectroscopy,1H-NMR spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analyses (TGA), polarizing optical microscopy (POM), and so on. Their structure-property relationships are discussed in detail. All the monomers and side-chain polymers are liquid crystals except the M3, M4and M7. M1and M2are thermal unilateral nematic liquid crystals. M5, M6, M8and M9are thermal enantiotropic nematic liquid crystals. M10is thermal enantiotropic cholesteric liquid crystal. Polymers P1～P3are thermal enantiotropic liquid crystals. For the polymers P1and P3series, with increasing of cholesteric liquid crystalline M10, the glass transition temperature (Tg) first decreased and then increased, the clearing point (Ti) increased. The polarizability of polymers P1and P3series is increased with the cholesteric monomer M10increasing. According to the result of TGA, the decomposed temperature of P1series are higher than290.0℃, it means they all have excellent stability. For the polymers P2series, with increasing of monomer M8, the glass transition temperature (Tg) first decreased and then increased, the clearing point (Ti) increased. |
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