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In this article, we designed and synthesized two novel swallow-tailed liquid crystal monomers (M1 and M2) with different chain lengths and rigidities centered on 3,4,5-trihydroxybenzoic acid and two series of side-chain liquid crystals polymers PN1 and PN2. All liquid crystal monomers and polymers were conformed to the molecular designs by FT-IR and NMR. The liquid crystal properties were tested by DSC and POM, and the results showed that M1 and M2 were thermotropic enantiotropic nematic liquid crystals and the side-chain liquid crystal polymers PN1 and PN2 series were typical amorphous liquid crystal polymers. With the increase of monomer content, the glass transition temperatures and clearing points of PN1 and PN2 series enhanced. With the increase of the number of mesogens in the liquid crystal monomer, the rigidity was enhanced, and the liquid crystal performance of the polymer was better. [ABSTRACT FROM AUTHOR]

In this study, two novel aromatic ester multi-arm liquid crystal monomers M1 and M2 with different terminal substituents centred on 3,4,5-trihydroxybenzoic acid, and a rod-shaped chiral liquid crystal monomer N were designed and synthesised. The synthesised liquid crystal monomers M and N were grafted and copolymerised with polymethylhydrosiloxane (PMHS). The structural characterisation of the synthesised liquid crystal compounds was carried out by FT-IR and 1H-NMR. The mesomorphic properties of the synthesised liquid crystal compounds were characterised by POM and DSC, and the results showed that the multi-arm liquid crystal monomers M1 and M2 are typical enantiotropic nematic liquid crystal compounds and N is typical thermotropic enantiotropic cholesteric liquid crystal. Polymers P1 and P2 are both cholesteric liquid crystal polymers. The glass transition temperatures and liquid crystal isotropic transition temperatures of polymers P1 and P2 series both tend to increase with the increase of multi-arm liquid crystal monomer M. [ABSTRACT FROM AUTHOR]

In this paper, two novel aromatic ester swallow-tailed liquid crystal monomers M1 and M2 and a straight chain cholesteric liquid crystal monomer M3 were designed and synthesised. Two series of liquid crystal polymers, P1 series and P2 series, were graft-copolymerised with M and polymethylhydrosiloxane (PHMS). All the synthesised liquid crystal monomers and polymers were characterised by IR and 1H NMR and confirmed to the predicted molecular structure. The liquid crystal and thermal properties of the synthesised compounds were tested by DSC, POM, TGA and optical rotation. The results show that the monomer M1 is a monotropic nematic liquid crystal, and the Schlieren texture appears during the cooling process. M2 is an enantiotropic nematic liquid crystal with filamentous and schlieren texture. M3 is a thermotropic enantiotropic cholesteric phase with oily streak and focal cone texture. Both polymers P1 and P2 show typical Grand-Jean texture, and with the increase of monomer M3 content, the polymer clearing point temperature Ti increases continuously, the liquid crystal mesophase range widens, and the specific rotation value increases. [ABSTRACT FROM AUTHOR]

In this paper, we designed and synthesised three Schiff base mesogenic units X-YP and six Y-shaped liquid crystal oligomers X-AYP and X-BYP (×= -CH3O, -CH3, -Cl). Molecular structures of the prepared compounds were confirmed via FT-IR, 1H NMR and elemental analysis. The mesomorphic properties were investigated by differential scanning calorimetry (DSC) and polarised light microscopy (POM). The photochemical properties of Y-shaped liquid crystal oligomers were preliminarily studied by UV-Vis spectrum. The results indicated that X-YP containing OCH3 and Cl substituents exhibited mesophase, while X-YP with CH3 substituent was non-mesogenic. The synthesized Y-shaped liquid crystals X-AYP and X-BYP both had liquid crystal properties and exhibited nematic phase during heating and cooling, which belonged to thermotropic enantiotropic nematic liquid crystals. The polarity of the terminal groups and the number of mesogenic units had a significant effect on the mesophase behaviour of Y-shaped liquid crystals. The absorption intensities of X-AYP and X-BYP in the UV spectra were affected by the terminal substituents. [ABSTRACT FROM AUTHOR]

In this paper, we designed and synthesised three H-shaped liquid crystal monomers ABOP-n (n = 4,6,8) and a straight-chain liquid crystal monomer M. Then, we used three H-shaped liquid crystal monomers as crosslinking agents, which were graft-copolymerised with M and polymethylhydrosiloxane (PMHS), respectively, to synthesise three series of liquid crystal elastomers P1–P3. The products were structurally well characterised by elemental analysis, 1HNMR, and FT-IR. The phase behaviours were investigated using the polarising microscope (POM) and differential scanning calorimetry (DSC). The results showed that ABOP-8, ABOP-6, ABOP-4 and M were thermotropic enantiotropic nematic liquid crystals, exhibiting schlieren texture during heating, and spherulite texture and schlieren texture during cooling. The photochemical properties of H-shaped liquid crystal monomers were preliminarily studied by UV-Vis spectra, and it was found that they have good photosensitivity. Both the P1–P3 series were typical non-crystalline polymers with anisotropic coloured textures. With the increase of crosslinking monomer content, the glass transition temperature of the P1–P3 series both increased, while the isotropic temperature showed a trend of first decreasing and then increasing. [ABSTRACT FROM AUTHOR]