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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 paper, a series of novel liquid crystal units (ASE-n, n = 4, 6, 8) of azo Schiff bases with sulphonic acid (-SO3H) as terminal substituents and different alkyl chain lengths were designed and synthesised. Nine star-shaped liquid crystal macromolecules with different central groups (ASE-P-n, ASE-T-n, ASE-G-n, n = 4, 6, 8) were synthesised by esterification of three novel azo Schiff base liquid crystal units (ASE-n, n = 4, 6, 8) with phloroglucinol, pentaerythritol and glucose. The structure of the synthesised compounds were analysed by infrared spectroscopy and 1H NMR. The results showed that all the compounds were consistent with the molecular structure design. The properties of liquid crystal such as phase transition temperature and liquid crystal mesophase range were characterised by POM and DSC. The effects of alkyl chain length and branched degree on the properties of liquid crystal were studied. The maximum absorption spectrum of the compound was determined by UV-Vis spectrophotometry. The photoisomerisation reaction of the compound was also studied. Under ultraviolet light (λ = 365 nm) irradiation, the effect of different duration on the cis-absorption percentage of azo (-N=N-) bond in the compound was studied. [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]

In this paper, we designed and synthesised two azo liquid crystal monomers (M1 and M2) and a chiral liquid crystal monomer N, followed by side-chain graft copolymerisation with polymethylhydrosiloxane (PMHS) to synthesize comb-like liquid crystalline polymers PN1 and PN2. The structures of all liquid crystal monomers and polymers conform to the molecular designs by FT-IR and 1H 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 N was a thermotropic enantiotropic cholesteric liquid crystal. Both the PN1 and PN2 series were amorphous polymers. The PN1 and PN2 series exhibited a typical Grand-jean texture. The glass transition temperature and isotropic temperature of the PN1 and PN2 series decreased first and then increased with the increase of azo monomer M content. And the glass transition temperature and isotropic temperature of the PN1 series were higher than the PN2 series. Both the PN1 and PN2 series had good thermal stability. The mesophase range of the PN1 series was 173.5°C~181.5°C, and the PN2 series was 162.5°C~172.9°C. [ABSTRACT FROM AUTHOR]

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]

Design and synthesis a series of azo multi-arm liquid crystal monomers (M1-M3) with cholic acid as the chiral core, followed by side chain graft copolymerisation with polymethylhydrosiloxane (PMHS) to synthesise the liquid crystal polymer PM series. All liquid crystal monomers and polymers were conformed to the molecular design in structure by FT-IR and NMR. The liquid crystal performance was tested by DSC and POM, and the results revealed that M1 and M2 were thermotropic enantiotropic cholesteric phase liquid crystals. Liquid crystal monomer M3 has no liquid crystal behaviour in both the up and down temperature processes. Polymers of the PM series exhibited different liquid crystal phases depending on the monomer content, with Grand-Jean texture at lower percentage and oil filament texture at higher percentage. The glass transition temperature and melting temperature decrease progressively with the increase in the liquid crystal monomer content, as opposed to the isotropic temperature. [ABSTRACT FROM AUTHOR]

Using tartaric acid as the core, six azo H-shaped liquid crystal compounds M1-M6 with different terminal substituents were synthesised. All products were structurally well characterised by elemental analysis, 1HNMR, and FT-IR. The phase behaviours were investigated by means of polarised optical microscopy and differential scanning calorimetry. M1-M6 were thermotropic enantiotropic nematic liquid crystals. They all showed schlieren texture in the process of heating up, and exhibited spherulite texture in the process of cooling down. M1 and M4 whose terminal substitution was nitro had the widest liquid crystal range in the same series of liquid crystal compounds, which were 135.1°C and 96.1°C, respectively, under heating cycle and 167.4°C and 112.7°C, respectively, under cooling cycle. The results show that the terminal substituents and flexible chain have important influence on the mesogenic phase and range. With the increase of flexibility, the mesogenic range of liquid crystal compounds becomes smaller when the end groups are the same. And when the flexible chain is the same, the greater the induced and polarised force of the terminal substituents, the better the mesogenic properties of the liquid crystal compounds. [ABSTRACT FROM AUTHOR]

A new series of polysiloxane glassy cholesteric liquid crystal copolymers with menthyl- and cholesteryl-based mesogenic units in the side chains, denoted as P-MtxChy (x, y expresses the molar ratio of monomers Mt and Ch in copolymeric synthesis, and x + y = 7.) were successfully synthesised by hydrosilylation reaction. The mesomorphic properties and phase behaviours were studied by differential scanning calorimetry (DSC), polarising optical microscopy (POM) and X-ray diffraction. Optical properties were investigated by the UV-VIS spectrum. Using the volume-excluding action of mesogenic units in side chains, we obtained glassy cholesteric liquid crystal copolymers. By varying molar ratio of Mt and Ch in copolymers, the helical pitch was adjusted into visible light region. With the increase of Mt, the maximum reflection wavelength off normal 8 ° shifted from 548 nm of P-Mt3Ch4 to 650 nm of P-Mt4Ch3 to 872 nm of P-Mt5Ch2, and the reflected colours changed from green to red. These well-oriented glassy films have shown good morphological stability below the glass-transition temperature (Tg) for more than a year. [ABSTRACT FROM AUTHOR]

Cholesteric liquid crystals with selective reflection have important applications in the field of light control and optical thin films. In this study, a series of side-chain cholesteric liquid-crystal polymers (named as PPL series) was synthesised by a one-step hydrosilylation reaction among monomer LA containing cholesterol group, monomer LB containing D(+)-camphoric acid group and monomer LG containing cyano group. The chemical structures and the mesogenic properties of the monomers and polymers were determined by usual test methods. Testing results showed that PPL series polymers had excellent thermal stability and wide range of mesophases. As the content of monomer LB increased, PPL1-PPL6 could be observed colourful Grandjean textures and good selective reflection. The optical rotation experiment indicated that the rotation direction of the PPL series was consistent with that of the monomer LB, and the specific rotation was linearly related to the content of the monomer LB. [ABSTRACT FROM AUTHOR]

A new series of glassy chiral-nematic liquid crystals P-ChxNy, were synthesised by hydrosilylation reaction of chiral mesogenic monomer Ch and nematic monomer N grafted onto polymethylhydrosiloxane. The mesomorphic properties, phase behaviour and selective reflection were studied by differential scanning calorimetry (DSC), polarising optical microscopy (POM), and UV-VIS spectrum. Both the Tg and Tc gradually increased as the amount of unit Ch in the copolymer increased. A series of morphologically stable, glassy chiral-nematic liquid crystals were obtained. Among these copolymers, the well-oriented glassy film of the polymer P-Ch4N3 exhibited a selective reflection band centred at approximately 532 nm with green reflected colour below Tg. Preparation and optical properties of linear polysiloxane-based glassy cholesteric liquid crystals with green reflected colour. [ABSTRACT FROM AUTHOR]

This paper designed and synthesised a series of V-shaped liquid crystal molecules (X-SBAnE) with resorcinol as the core and Schiff base as the mesogenic arms (X-SBAAn). The effects of polarity of terminal groups (X=-CH3O,-CH3,-Cl) and length of flexible chain (n = 4,6,8) on mesogenic ranges were discussed. The chemical structure of X-SBAAn and X-SBAnE was studied using FT-IR and 1H-NMR while their thermal behaviour and mesogenic ranges were investigated via differential scanning calorimetry (DSC) and polarising optical microscopy (POM). The results indicated that X-SBAAn containing OCH3 and Cl substituents exhibited mesophase except for the analogue having CH3 substituent which was found to be non-mesogenic. All of the synthesised X-SBAnE had liquid crystal properties and exhibited nematic phases in heating and cooling. The length of the flexible spacers and terminal groups significantly influenced their mesogenic ranges. [ABSTRACT FROM AUTHOR]

A series of symmetric liquid crystal (LC) dimers with the same chiral core (S)-1-phenylethane-1,2-diol ((S)-PE) have been synthesised, termed TBDA-(S)-PE, 3F3B-(S)-PE, 3F2B-(S)-PE, 1F3B-(S)-PE, 1F2B-(S)-PE, respectively. Chemical structures and LC properties of the five symmetric LC dimers were characterised by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance hydrogen spectrometer (1H NMR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and polarised optical microscopy (POM). TBDA-(S)-PE displayed enantiotropic chiral smectic A (SmA*) phase while 3F3B-(S)-PE, 3F2B-(S)-PE, 1F2B-(S)-PE all displayed enantiotropic chiral nematic (N*) phase and 1F3B-(S)-PE displayed monotropic N* phase. The results indicated that the removal of the flexible spacers between the rigid mesogenic arm and the chiral core facilitated the formation of the N* phase. When the rigid mesogenic units are connected to the chiral core directly, the structure of the terminal fluorine group and the rigidity of the mesogenic unit played certain influence on the thermal properties of the LC dimers, but did not change the type of mesomorphic phase. Compared to 3F3B-(S)-PE and 1F3B-(S)-PE, 3F2B-(S)-PE and 1F2B-(S)-PE displayed wider LC ranges, respectively, suggesting molecular regularity had greater influence on LC-isotropic (I) transition temperature. [ABSTRACT FROM AUTHOR]

In this study, we synthesised two series of cholesteric liquid crystal polymers CPQ and CPZ series. First, we prepared four different monomers ML1 containing a cholesteryl group, ML2 containing a cyano group, ML3 containing a phenolic hydroxyl group and ML4 containing isosorbide with azo groups. With the polymethylsiloxanes as the main chain, CPQ series were then synthesised by copolymerisation among the monomers ML1, ML2 and ML3 and CPZ series were synthesised by esterification between the CPQ series and the monomer ML4. 1HNMR and FT-IR spectra confirmed the chemical structures of all the monomers and polymers. The mesomorphic behaviours and thermal properties were investigated by TGA, DSC, POM and XRD. Both the CPQ and CPZ series exhibited excellent thermal stability and reversible phase transitions, as well as interesting Grandjean textures under POM. CPZ series showed higher optical activity than CPQ series due to the introduction of the isosorbide group and the azo group, which could tune the pitch to make Bragg selective reflection appear more easily. UV–Vis spectra investigated the photoresponse behaviours of CPZ series thoroughly. [ABSTRACT FROM AUTHOR]

Two series of novel four-arm azobenzene liquid crystal molecules were designed and synthesized, and their mesophase properties, photo-induced transition were studied. Two series of mesogenic arms were screened with different length of flexible chain (the carbon number n of flexible chain is 4, 6, 8, 10) using methoxy and nitro as terminal substituents R. The four-arm azobenzene LCs were synthesized by introducing the mesogenic arms into cholic acid. FACAE-O-n, FACAE-N-n all belonged to photosensitive thermotropic enantiotropicnematic LCs. For methoxyl series, melting transitions (Tm), liquid crystal-isotropic transitions (Ti) and mesogenic ranges decreased with the increase of carbon numbers in flexible chain both on heating and cooling. The mesophase performance of FACAE-O-4 was the most excellent. For nitro series, Tm and Ti on heating and cooling decreased with the increase of carbon numbers. Nevertheless, mesogenic ranges increased with the increase of carbon numbers only on heating. The cooling mesogenic ranges showed a trend of rising firstly and then falling, reaching the maximum 103.1oC (n=8). Under ultraviolet irradiation, there was no red shift. The intensity of maximum absorption has changed with the increase of ultraviolet irradiation time. After photo-induced, Tm and Ti on heating and cooling of the four-arm LCs decreased, and the mesogenic ranges became shorter. [ABSTRACT FROM AUTHOR]

We synthesized two series of cholesteric liquid-crystal elastomers by hydrosilylation among monomers MA containing a cholesteryl group, MB (MC) containing a phenolic hydroxyl group and MD as the crosslinker. The chemical structures of all the monomers and LCEs were confirmed by 1H NMR and FT-IR. We explored the mesomorphic properties and phase behaviours by TGA, DSC, POM, and XRD. All the LCEs presented elasticity, reversible phase transition, and high thermal stability. For two series of LCEs, the glass transition temperature increased slowly, and the isotropic transition temperature increased obviously. PA-I-PA-V and PB-I-PB-IV displayed selective reflection and colourful Grandjean texture, but PA-VI, PB-V, and PB-VI needed external pressure to show them. [ABSTRACT FROM AUTHOR]

A series of novel azobenzene chiral liquid crystals (Mt4AZOnB) containing (-)-menthyl were successfully synthesised. Terminal alkyl chains of the molecules varied from methyl to hexyl. The chemical structures were characterised by Fourier transform infrared and 1H-NMR spectra. Liquid crystalline behaviour of the chiral liquid crystals was characterised by differential scanning calorimetry and polarising optical microscopy. The effect of terminal alkyl chains on mesomorphic and photoisomerisation behaviour of azobenzene-based liquid crystals is discussed. The lower members (n = 1, 2, 3, 4) are monotropic and only the higher members (n = 5, 6) show enantiotropic behaviour. These compounds show a distinct odd-even effect for the phase transition temperature when the parity of the terminal chain is varied. [ABSTRACT FROM AUTHOR]

A new nematic liquid crystalline polymer as a highly active β-nucleator (LCP-N) of isotactic polypropylene (iPP) was synthesized and characterized. The effect of LCP-N on thermal behavior of the iPP was investigated with differential scanning calorimetry. LCP-N showed a melting transition at 85.0°C and a nematic to isotropic phase transition at 278.0°C. The incorporation of LCP-N could lead to substantial changes in the thermal behavior of the iPP. The nucleating activity of LCP-N mainly depended on its content, mesogenic molecular structure, and thermal history of processing. A high content of β-form could be obtained by the combined effect of the optimum LCP-N concentration and crystallization temperature and time. The Φβreached 77% when the LCP-N content, crystallization temperature, and crystallization time were 0.4 wt.%, 125°C, and 1 h, respectively. [ABSTRACT FROM AUTHOR]

The synthesis of new chiral monomer 4-(menthyloxyacetoxy- benzoyloxy)biphenyl-4′-(2-(undec-10-e noyloxy)ethoxy)benzoate (ML), crosslinking agent 4-(undec-10-enoyloxy)biphenyl-4′-(2-(undec-10-enoyloxy)ethoxy)benzoate (CA), and liquid crystal polymer networks (E1−E5) containing menthyl group is presented. Their chemical structures and phase behavior were characterized with Fourier transform infrared (FT-IR), proton nuclear magnetic resonance (1H-NMR), elemental analyses, polarizing optical microscopy, differential scanning calorimetry, thermogravimetric analysis (TGA), and X-ray diffraction. The selective reflection of light for ML was investigated with ultraviolet/visible/near infrared (UV/Visible/NIR). By inserting a flexible spacer between the mesogenic core and the terminal menthyl groups, MLcould form mesophase and show a chiral smectic C phase, cholesteric phase and cubic blue phase. CA displayed a smectic A phase and nematic phase. The polymer networks containing less than 12 mol% of the crosslinking units showed reversible cholesteric phase transition, wide mesophase temperature range, and excellent thermal stability. With increasing the content of crosslinking unit, the corresponding Tg increased, the Ti decreased, and the mesophase temperature range narrowed for E1−E5. TGA showed that the Td(5%) was greater than 330°C for E1−E5. [ABSTRACT FROM AUTHOR]

The synthesis of new chiral liquid crystal monomers (M1 −M4 ) derived from menthyl groups, the corresponding smectic polymers (P1 −P4 ), and cholesteric elastomers (E1 −E4 ) based on M2 and crosslinking agent (CA ) is presented. The chemical structures and purity were characterised by Fourier transform infrared, 1H nuclear magnetic and elemental analyses. The phase behaviour and mesomorphism were investigated by differential scanning calorimetry, polarising optical microscopy, thermal gravimetric analysis and X-ray diffraction. The selective reflection of light for M1 −M4 was characterised with ultraviolet/visible/near infrared. The structure–property relationships of M1 −M4 and P1 −P4 were studied. The effect of the content of mesogenic crosslinking units on phase behaviour and mesomorphism of E1 −E4 was discussed. By inserting a flexible spacer between the mesogenic core and the terminal menthyl groups, M1 −M4 all showed strong mesomorphism and exhibited an oily streak and focal conic textures of the cholesteric phase, or the broken fan-shaped texture of the smectic C* phase and the platelet texture of a cubic blue phase. P1 −P4 exhibited batonnet textures of the smectic A phase, indicating that the liquid crystal polymers with siloxane chains tended to form a lower order smectic phase. For M1 −M4 or P1 −P4 , the melting temperature Tm , the isotropic temperature Ti and the glass transition temperature Tg increased, and the mesophase temperature range widened with increasing rigidity of the mesogenic units or decreasing spacer length. E1 −E4 exhibited a cholesteric texture because of the introduction of the nematic crosslinking unit. By increasing the content of the crosslinking unit, the general tendency is toward increased Tg and decreased Ti . [ABSTRACT FROM PUBLISHER]

• Seven novel CLCs M n AZO2B were synthesized by varying spacer between (-)-menthyl and mesogenic core. • The effect the position of (-)-menthyl on mesomorphic behaviors was disscussed. • Only CLCs M n AZO2B with short spacer revealed selective reflection for visible light and blue phase. • An odd-even effect was observed as the spacer length gradually increased. As the mesomorphic type of liquid crystals could be largely altered by the molecular chirality, we herein explored the effect of position of chiral (-)-menthyl on the mesomorphic and photoisomerization behavior in azobenzene liquid crystals. By modifying the position of chiral (-)-menthyl in the menthol based liquid crystal compounds through gradually increasing the alkyl chain length of the dicarboxylic spacer, seven new chiral liquid crystal compounds 4-(4-menthyloxy-n-oxoalkanoyloxy)-4′-(4-ethoxybenzoyloxy) azobenzene M n AZO2B (n = 2–8) were prepared. A combination of analysis methods was conducted to systematically investigate their structures, mesophase behaviors and optical properties. The length and parity of the flexible spacers has a dramatic influence on the mesomorphic behaviors, and an odd-even effect is observed for these chiral liquid crystal compounds. [Display omitted] [ABSTRACT FROM AUTHOR]

• Three novel unreported mesogens were designed and synthesized, in which the azo and Schiff base were conjugated. • Three series of novel branched azo-Schiff base liquid crystal oligomers were designed and synthesized. • 4-hydroxybenzoic acid, 3,5-dihydroxybenzoic acid, 3,4,5-trihydroxybenzoic acid as the center and cholesterol as the chiral group. • The mesomorphic properties change regularly with the branching degree and rigidity and flexibility of the liquid crystal macromolecules. Three novel azo-Schiff base mesogens with different alkyl chain lengths and three series of novel branched liquid crystal oligomers with 4-hydroxybenzoic acid, 3,5-dihydroxybenzoic acid, 3,4,5-trihydroxybenzoic acid as the center and cholesterol as the chiral group were designed and synthesized. The test results showed that their liquid crystal phase behavior was closely related to the number of mesogenic units and the rigidity and flexibility of the structure. In the same series, as the value of n increased, the mesophase ranges were widened. When the value of n was the same in different series, as the degree of branching increased, the mesophase ranges were widened. [Display omitted] [ABSTRACT FROM AUTHOR]

• Eight novel CLCs MtLC - X were synthesized by varying the electron-donating/withdrawing substituents X in terminal groups. • The effect of polar group X on mesomorphic behaviros of chiral (-)-menthanol based CLCs was disscussed. • By DFT calculations the relationship between mesomorphic behaviros and polarizability anisotropy (Δα) was investigated. • The effect of polar group X on the formation of blue phase of CLCs MtLC-X were studied. Eight novel Schiff base ester chiral liquid crystals, MtLC-X (X : -OCH 3 , -CH 3 , -F, -H, -CF 3 , -OCF 3 , -NO 2 , -CN), were successfully synthesized and analyzed for their mesophase formation and stability. Each of them was attached to the end of (-)-menthol as a chiral group, and the other end of these molecules was connected with different polar substituent X. The chemical structures of the prepared compounds were characterized via FT-IR, 1H NMR and 13C NMR. The combination differential scanning calorimeter (DSC), polarizing optical microscopy (POM) and X-ray diffraction (XRD) measurements were carried out to systematically study the characterization of mesomorphic properties. The photophysical property was studied by UV–vis spectroscopy. All the prepared CLCs, besides the H derivative, MtLC H, are mesomorphic exhibiting N* and/or S A * mesophase. The results revealed that the mesomorphic behavior and the clearing point of mesophase (T c) correlate well with polarizability anisotropy (Δα). [Display omitted] [ABSTRACT FROM AUTHOR]

With polymethylhydrogensiloxane (PMHS) as the main chain, two series side-chain cholesteric liquid crystal polymers (ChLCPs) with different liquid crystal side chain lengths were prepared by hydrosilylation reaction. Then two series of cholesteric fluorescent liquid crystal polymers (FL-ChLCPs) were obtained by etherification reaction. The obtained FL-ChLCPs have both excellent mesomorphic behavior, and great photoluminescent property. We confirmed their chemical structures by FT-IR, and 1H NMR spectroscopy, and found them with excellent thermal stability by TGA. We characterized their mesomorphic behavior and thermal performance by POM, DSC and XRD, and confirmed all the polymers belonged to cholesteric phase. FL-ChLCPs emitted different-intensity fluorescence under UV light, and we found some regularity by PL spectrum. Image 1 • Cholesteric fluorescent liquid crystal polymers were synthesized using a new method. • FL-ChLCPs have both excellent mesomorphic behavior, and great photoluminescent property. • FL-ChLCPs are sensitive to temperature, and the temperature-dependent fluorescence is reversible. [ABSTRACT FROM AUTHOR]