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Three series of new branched liquid crystal oligomers with 4-hydroxybenzoic acid, 3,5-dihydroxybenzoic acid, 3,4,5-trihydroxybenzoic acid as the centre and cholesterol as the chiral group were designed and synthesised (Dn, Fn and Hn, n = 4,6,8). DSC and POM results showed that their liquid crystal phase behaviour was closely related to the number of mesogenic unit and the rigidity and flexibility of the structure. They were all cholesteric liquid crystals. In the same series, as the value of n increased, the mesophase ranges became narrower. When the value of n was the same in different series, as the degree of branching increased, the mesophase ranges became narrower. [ABSTRACT FROM AUTHOR]

A series of star-shaped liquid crystal (LC), respectively, based on phloroglucinol, pentaerythritol and glucose as cores, rod-shaped molecules (MeOSBAA, MeSBAA and ClSBAA) containing a schiff base as mesogenic mesogen were synthesised. The molecular structures were confirmed by FT-IR and 1H-NMR techniques. The LC textures and thermal phase behaviours were investigated by polarising optical microscopy and differential scanning calorimetry. The results showed that MeOSBAA and ClSBAA were thermally enantiotropic liquid crystals. Three-arm star LC macromolecules X-SBA3E and four-arm star LC macromolecules X-SBA4E were found to display enantiotropic nematic liquid crystals behaviour. While the five-arm star-shaped chiral LC molecules X-SBA5E exhibited enantiotropic chiral nematic phase. [ABSTRACT FROM AUTHOR]