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Mesomorphic Properties (mesomorphic + property)
Selected AbstractsSynthesis and Mesomorphic Properties of Some , ,-Alkoxy- , -benzoxypolyfluorotolane CompoundsCHINESE JOURNAL OF CHEMISTRY, Issue 7 2006Chuan Qing Abstract Four homologue series of 4-cyano- and 4-nitro-substituted benzoate-tolanes were synthesized and characterized by IR, NMR, MS spectra and elemental analysis. Their phase transition behaviors were investigated by DSC and polarized optical microscope. The effects on the mesomorphic properties of different positions of the perfluorophenyl in the molecular core unit, the terminal cyano-substituted systems and the terminal nitro-substituted ones were discussed. [source] Synthesis and Mesomorphic Properties of 4-((4- n -Alkoxy-2, 3, 5, 6-tetrafluorophenyl)ethynyl)phenyl Methoxy-substituted BenzoatesCHINESE JOURNAL OF CHEMISTRY, Issue 5 2001Heng-Feng Li Abstract Two series of 4-methoxybenzoate liquid crystals were synthesized. Their phase transition temperatures were also measured by texture observation in a polarizing microscope and confirmed by DSC. Their mesomorphic properties and fluoro-substitute effect were studied in detail. [source] Oligo(triacetylene) Derivatives with Pendant Long Alkyl ChainsHELVETICA CHIMICA ACTA, Issue 6 2004Jean-François Nierengarten Substituted (E)-2-(ethynyl)but-2-ene and (E)-hex-3-ene-1,5-diyne derivatives 6 and 10, respectively, were prepared by dicyclohexylcarbodiimide(DCC)-mediated esterification of tris(dodecyloxy)benzoic acid (4) with (E)-2-[(triisopropylsilyl)ethynyl]but-2-ene-1,4-diol (3) and (E)-2,3-bis[(trimethylsilyl)ethynyl]but-2-ene-1,4-diol (8), respectively, followed by deprotection with Bu4NF in wet THF (Schemes,1 and 2). Oligomerization reactions of diyne derivative 10 were attempted by treatment with the Hay catalyst in the presence of mono-alkyne 6 as an end-capping reagent. Under these conditions, only compound 7 resulting from the homocoupling of 6 (Scheme,1), and polymers of 10 were obtained due to the difference in reactivity of the alkyne groups in 6 and 10. In contrast, when phenylacetylene was used as the stopper, the oligomerization of 10 afforded a mixture of end-capped oligomers, from which 11,13 were isolated by column chromatography (Scheme,3). The poly(triacetylenes) (PTA) 16,18 were prepared in a similar manner starting from diol 8 and stearic acid (Schemes,4 and 5). Whereas the end-capped monomers and dimers 11, 12, 16, and 17 with pendant long alkyl chains do not exhibit any liquid-crystalline behavior, the trimeric derivatives 13 and 18 show mesomorphic properties, thus demonstrating that the poly(triacetylene) backbone can behave as a mesogenic unit. [source] Synthesis and liquid crystalline properties of poly(1-alkyne)s carrying triphenylene discogensJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2008Changmin Xing Abstract Triphenylene-containing 1-decynes with different alkyl chain lengths and their polymers are synthesized and the effects of the structural variables on their mesomorphic properties are investigated. The monomers [HCC(CH2)8CO2C18H6 (OCmH2m+1)5; m = 4,9] are prepared by consecutive etherization, coupling, and esterification reactions. The monomers form columnar phases at room temperature. The polymerizations of the monomers are effected by [Rh(nbd)Cl]2, producing soluble polymers in high yields (up to 84%). The structures and properties of the polymers are characterized and evaluated by IR, NMR, TGA, DSC, POM, and XRD analyses. All the polymers are thermally stable, losing little of their weights when heated to 300 °C. The isotropization temperature of the polymers increases initially with the length of alkyl chain but decreases on further extension. Although the polymers with shorter and longer alkyl chain lengths adopt a homogeneous hexagonal columnar structure, those with intermediate ones form mesophases with mixed structures. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2960,2974, 2008 [source] Lightly crosslinked, mesomorphic networks obtained through the reaction of dimeric, liquid-crystalline epoxy,imine monomers and heptanedioic acidJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2006David Ribera Abstract We reacted various dimeric, liquid-crystalline epoxy,imine monomers, differing in the length of the central aliphatic spacer or the dipolar moments, with heptanedioic acid. The resulting systems showed a liquid-crystalline phase in some cases, depending on the dimer and on the reaction conditions. The systems were characterized with respect to their mesomorphic properties and then were submitted to dynamic mechanical thermal analysis in both fixed-frequency and frequency-sweep modes in the shear sandwich configuration. The arrangement in the liquid-crystalline phase seemed to be mainly affected both by the polarization of the mesogen and by the reaction temperature, which favored the liquid-crystalline arrangement when it was lying in the range of stability of the dimer mesophase. In agreement with other recent literature data, dynamic mechanical thermal analysis results suggested that the presence of the mesogen directly incorporated into the main chain increased the lifetimes of the elastic modes both in the isotropic phase and in the liquid-crystalline phase with respect to side-chain liquid-crystalline elastomers and that the time,temperature superposition principle did not hold through the liquid-crystalline-to-isotropic transition. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44:6270,6286, 2006 [source] Synthesis and Characterization of Supramolecular Polymeric Materials Containing Azopyridine UnitsMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 22 2006Marta Millaruelo Abstract Summary: The synthesis and characterization of a series of supramolecular polymeric complexes formed by H-bonding interactions between benzoic acid and azopyridine derivatives are described. A series of polymeric networks have been synthesized using a polymethacrylate bearing benzoic acid units as side groups, and several polymers with azopyridine as H-acceptor side groups. Furthermore, low-molecular-weight pyridine derivatives have been used to prepare an homologous side-chain polymer, and a network with azopyridine as a non-covalent crosslinker. Special attention was paid to the thermal and mesomorphic properties of these materials, which were studied by DSC, POM, and XRD. Micrograph of the mesomorphic melt of a sample taken at 130,°C on cooling from the isotropic state. [source] Synthesis and characterization of liquid crystalline elastomers bearing fluorinated mesogenic units and crosslinking mesogensPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 12 2009Fan-Bao Meng Abstract Several new side-chain liquid crystalline (LC) polysiloxanes and elastomers (IP - VIP) bearing fluorinated mesogenic units and crosslinking mesogens were synthesized by a one-step hydrosilylation reaction with poly(methylhydrogeno)siloxane, a fluorine-containing LC monomer 4,-undec-10-enoyloxy-biphenyl-4-yl 4-fluoro-benzoate and a crosslinking LC monomer 4,-(4-allyloxy-benzoxy)-biphenyl-4-yl 4-allyloxy-benzoate. The chemical structures and LC properties of the monomers and polymers were characterized by use of various experimental techniques such as FTIR, 1H-NMR, EA, TGA, DSC, POM and XRD. The effect of crosslinking mesogens on mesomorphic properties of the fluorinated LC polymers was studied as well. The obtained polymers and elastomers were soluble in many solvents such as toluene, tetrahydrofuran, chloroform, and so forth. The temperatures at which 5% weight loss occurred (Td) were greater than 250°C for all the polymers, and the weight of residue near 600°C increased slightly with increase of the crosslinking mesogens in the fluorinated polymer systems. The samples IP, IIP, IIIP and IVP showed both smectic A and nematic phases when they were heated and cooled, but VP and VIP exhibited only a nematic mesophase. The glass transition temperature (Tg) of polymers increased slightly with increase of crosslinking mesogens in the polymer systems, but the mesophase,isotropic phase transition temperature (Ti) and smectic A,nematic mesophase transition temperature (TS-N) decreased slightly. It suggests that the temperature range of the mesophase became narrow with the increase of crosslinking mesogens for all the fluorinated polymers and elastomers. In XRD curves, the intensity of sharp reflections at low angle decreased with increase of crosslinking mesogens in the fluorinated polymers systems, indicating that the smectic order derived from fluorinated mesogenic units should be destroyed by introduction of more crosslinking mesogens. Copyright © 2008 John Wiley & Sons, Ltd. [source] Synthesis and Mesomorphic Properties of Some , ,-Alkoxy- , -benzoxypolyfluorotolane CompoundsCHINESE JOURNAL OF CHEMISTRY, Issue 7 2006Chuan Qing Abstract Four homologue series of 4-cyano- and 4-nitro-substituted benzoate-tolanes were synthesized and characterized by IR, NMR, MS spectra and elemental analysis. Their phase transition behaviors were investigated by DSC and polarized optical microscope. The effects on the mesomorphic properties of different positions of the perfluorophenyl in the molecular core unit, the terminal cyano-substituted systems and the terminal nitro-substituted ones were discussed. [source] Synthesis and Mesomorphic Properties of 4-((4- n -Alkoxy-2, 3, 5, 6-tetrafluorophenyl)ethynyl)phenyl Methoxy-substituted BenzoatesCHINESE JOURNAL OF CHEMISTRY, Issue 5 2001Heng-Feng Li Abstract Two series of 4-methoxybenzoate liquid crystals were synthesized. Their phase transition temperatures were also measured by texture observation in a polarizing microscope and confirmed by DSC. Their mesomorphic properties and fluoro-substitute effect were studied in detail. [source] | |||||||||||||