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1.
Xiao‐Zhi He Bao‐Yan Zhang Corresponding author Jian‐She Hu Mei Tian 《Liquid crystals》2013,40(3):299-306
In this work we prepared a nematic monomer (4′‐allyloxybiphenyl 4′‐ethoxybenzoate, M1 ), a chiral crosslinking agent (isosorbide 4‐allyloxybenzoyl bisate, M2 ) and a series of new side chain cholesteric liquid crystalline elastomers derived from M1 and M2 . The chemical structures of the monomers and polymers were confirmed by FTIR and 1H NMR spectroscopy. The mesomorphic properties were investigated by differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy and X‐ray diffraction. The effect of the content of the crosslinking unit on phase behaviour of the elastomers is discussed. Polymer P1 showed a nematic phase, P2 –P7 showed a cholesteric phase; P6 formed a blue Grandjean texture over a broad temperature range 145–209.6°C, with no changed on the cooling. Polymers P4 –P7 , with more than 6?mol?% of chiral crosslinking agent, gave rise to selective reflection. Elastomers containing less than 15?mol?% of the crosslinking units displayed elasticity, reversible phase transition with wide mesophase temperature ranges, and high thermal stability. Experimental results demonstrated that, with increasing content of crosslinking agent, the glass transition temperatures first fell and then increased; the isotropization temperatures and mesophase temperature ranges decreased. 相似文献
2.
In this work the new-style nematic monomer M1 , chiral crosslinking reagent MC and a series of new side-chain cholesteric liquid crystalline elastomers derived from M1 and MC were prepared. The effect of the content of the chiral crosslinking unit on phase behaviour of the elastomers has been discussed. Polymer P1 showed nematic phase, P2 –P7 showed cholesteric phase, P3 formed Grandjean texture in the heating cycle and turned out a blue Grandjean texture in the cooling cycle, P2 –P3 with less than 6 mol% of chiral crosslinking agent gave rise to selective reflection. The elastomers containing less than 15 mol% of the crosslinking units displayed elasticity, reversible phase transition and high thermal stability. Experimental results demonstrated that the glass transition temperatures reduced first and then increased, and the isotropisation temperatures and the mesophase temperature ranges decreased with increasing content of crosslinking unit. 相似文献
3.
Synthesis and characterization of a series of side chain chiral smectic liquid crystalline elastomers 总被引:1,自引:0,他引:1
A series of new chiral smectic liquid crystalline elastomers was prepared by graft polymerization of a nematic monomer with a chiral and non-mesogenic crosslinking agent, using polymethylhydrosiloxane as backbone. The chemical structures of the monomers and polymers obtained were confirmed by FTIR and 1H NMR. The mesomorphic properties were investigated by differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy and X-ray diffraction. Monomer M1 showed a nematic phase during heating and cooling. Polymer P0 exhibited a smectic B phase; elastomers P1-P3 showed the smectic A phase, P4-P6 showed a chiral smectic C(SmC*), and P7 displayed stress-induced birefringence. Elastomers containing less than 15 mol % M2 displayed elasticity, reversible phase transitions with wide mesophase temperature ranges, and high thermal stability. With increasing content of the crosslinking unit, glass transition temperatures first increased, then fell, then increased again; isotropization temperatures and mesophase temperature ranges steadily decreased. 相似文献
4.
Jian‐She Hu Bao‐Yan Zhang Ai‐Juan Zhou Yan‐Li Dong Zhan‐Xiang Zhao 《Journal of polymer science. Part A, Polymer chemistry》2005,43(15):3315-3323
A series of new side‐chain cholesteric elastomers derived from cholesteryl 4‐(10‐undecylen‐1‐yloxy)‐4′‐ethoxybenzoate and phenyl 4,4′‐bis(10‐undecylen‐1‐yloxybenzoyloxy‐p‐ethoxybenzoate) was synthesized. The chemical structures of the monomers were confirmed by elemental analyses, Fourier transform infrared, and 1H NMR and 13C NMR spectra. The mesomorphic properties of elastomers were investigated with differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy, and X‐ray diffraction measurements. The influence of the content of the crosslinking unit on the phase behavior of the elastomers was examined. Monomer M1 showed a cholesteric phase, and M2 displayed smectic and nematic phases. The elastomers containing <15 mol % of the crosslinking units revealed reversible mesomorphic phase transition, wide mesophase temperature ranges, and high thermal stability. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3315–3323, 2005 相似文献
5.
Bao-Yan Zhang Jian-She Hu Bai Wang Dan-Shu Yao Hao Li 《Colloid and polymer science》2007,285(15):1683-1690
New liquid crystalline monomer 4-(4-ethoxybenzoyloxy)biphenyl-4′-[(10-undecylen-1-yloxy)-4′-ethoxy]benzoate (M
1
), chiral crosslinking agent isosorbide di-(10-undecylen-1-yloxybenzoate) (M
2
), and the corresponding elastomers were prepared. The chemical structures of M
1
and M
2
were characterized by Fourier transform infrared and 1H-nuclear magnetic resonance. The mesomorphic properties and phase behavior were investigated by differential scanning calorimetry,
thermogravimetric analysis, polarizing optical microscopy, and X-ray diffraction measurements. M
1
exhibited typical threaded texture and droplet texture of nematic phase. The use of chiral crosslinking agent in the polymer
networks could induce cholesteric phase. The elastomers containing less than 10 mol% of the chiral crosslinking units showed
elasticity, reversible phase transition, wide mesophase temperature ranges, and high thermal stability. For the elastomers
P
2
–P
4
, the glass transition temperature (T
g) increased; clearing temperature (T
i) and mesophase temperature range (ΔT) decreased with increasing content of the crosslinking unit. 相似文献
6.
Jian-She Hu Bao-Yan Zhang Mei Tian Shi-Chao Ren Deng-Yuan Guo 《Colloid and polymer science》2005,283(12):1349-1355
New monomer cholesteryl 4-(10-undecylen-1-yloxybenzoyloxy)-4′-ethoxybenzoate (M1), crosslinking agent biphenyl 4,4′-bis(10-undecylen-1-yloxybenzoyloxy-p-ethoxybenzoate) (M2) and a series of side-chain cholesteric elastomers were prepared. The chemical structures of the monomers and elastomers
obtained were confirmed by element analyses, FT-IR, and 1H NMR. The mesomorphic properties and thermal stability were investigated by differential scanning calorimetry, thermogravimetric
analysis, polarizing optical microscopy, and X-ray diffraction measurements. The influence of the content of the crosslinking
unit on the phase behavior of the elastomers was examined. M
1
showed cholesteric phase, and M
2
displayed nematic phase. The elastomers containing less than 12 mol% of the crosslinking units revealed reversible mesomorphic
phase transition, wide mesophase temperature ranges, and high thermal stability. 相似文献
7.
The synthesis of new side-chain cholesteric elastomers derived from a cholesteric monomer and mesogenic crosslinking agent is presented. The chemical structures of the monomers obtained were confirmed by elemental analyses, FT-IR, 1H NMR, and 13C NMR. The mesomorphic properties and thermal stability were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), polarizing optical microscopy (POM), and X-ray diffraction (XRD) measurements. M1 showed cholesteric phase, and M2 displayed enantiotropic nematic phase and monotropic smectic phase. The elastomers containing less than 12 mol% of the crosslinking units revealed reversible mesomorphic phase transition, wide mesophase temperature ranges, and high thermal stability. 相似文献
8.
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. 相似文献
9.
In this work we prepared a nematic monomer (4'-allyloxybiphenyl 4'-ethoxybenzoate, M1), a chiral crosslinking agent (isosorbide 4-allyloxybenzoyl bisate, M2) and a series of new side chain cholesteric liquid crystalline elastomers derived from M1 and M2. The chemical structures of the monomers and polymers were confirmed by FTIR and 1H NMR spectroscopy. The mesomorphic properties were investigated by differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy and X-ray diffraction. The effect of the content of the crosslinking unit on phase behaviour of the elastomers is discussed. Polymer P1 showed a nematic phase, P2-P7 showed a cholesteric phase; P6 formed a blue Grandjean texture over a broad temperature range 145-209.6°C, with no changed on the cooling. Polymers P4-P7, with more than 6 mol % of chiral crosslinking agent, gave rise to selective reflection. Elastomers containing less than 15 mol % of the crosslinking units displayed elasticity, reversible phase transition with wide mesophase temperature ranges, and high thermal stability. Experimental results demonstrated that, with increasing content of crosslinking agent, the glass transition temperatures first fell and then increased; the isotropization temperatures and mesophase temperature ranges decreased. 相似文献
10.
ABSTRACTTwo series of novel side-chain liquid crystal (LC) polysiloxanes grafted with chiral liquid crystalline dimers containing cholesteryl mesogens were synthesised. The chemical structure and LC properties of comonomers and polymers were characterised by FTIR, 1H-NMR, DSC, TGA, POM and XRD. M1 and M2 were chiral nematic (N*) dimers, and M3 was an achiral LC monomer displaying nematic mesophase in a narrow mesomorphic temperature range, while the copolymers exhibited N* mesophase whose mesomorphic temperature ranges were much wider than those of the comonomers. Moreover, the glass transition temperatures and isotropization temperatures of the polymers all decreased with decreasing the dimer components. Reflection spectra showed that Pa series tend to attain wide-band selective reflection at long wavelengths, while Pb series were more potential at short wavelengths with narrow bandwidths. Decreasing the dimer components led the wavelength of the selective reflection to blue shift, which was an abnormal phenomenon in chiral mixture system. 相似文献
11.
A new series of side-chain chiral liquid crystalline elastomers derived from M1 (cholest-5-3-ol(3β)-4-(2-propen-yloxy)]benzoate) and MC(2,5-[3,5-bis(4-(3-(4-(allyloxy)phenyl)propanoyloxy)benzoyloxy)benzoic acid]isosorbide diester). The structures of monomers and elastomers measured by using Proton Nuclear Magnetic Resonance Spectra (1H-NMR) and Fourier transform infrared spectroscopy (FTIR) separately are consistent with our design. IIP~VIP all appeared blue Grandjean (GJ) texture on the heating cycle or cooling cycle. The glass sheets of IIP~VIP were made under 150°C and measured its ultraviolet–visible spectrophotometry by PerkinElmer Lambda 950 instrument (Shelton, CT, USA). IIP~VIP all have absorptions at about 481~483 and 561~562 nm. The optical activities were measured at different temperatures on heating and cooling cycles. And the blue selective reflection of IIP~VIP on the round glass sheet can be seen. The elastomers containing less than 6 mol% of the crosslinking units displayed elasticity, reversible phase transition and high thermal stability. The glass transition temperatures reduced first and then increased, the isotropisation temperatures and the mesophase temperature ranges increased first and then decreased with increasing content of crosslinking unit. The thermogravimetric analysis (TGA) results showed that the temperatures at which 5% weight loss occurred (Td) were greater than 310°C for all the polymers. 相似文献
12.
The synthesis of two cholesteric monomers (M1 and M2), nematic crosslinking agent (C1 and C2), and the corresponding side-chain elastomers containing menthyl groups (P1 and P2 series) is described. The mesomorphism was investigated by differential scanning calorimetry, polarizing optical microscopy,
X-ray diffraction, and thermogravimetric analysis. The effect of the content of the different nematic crosslinking unit on
the mesomorphism of the elastomers was discussed. M1 and M2 showed cholesteric and blue phases; C1 and C2 showed nematic phase. Because of the introduction of the nematic crosslinking unit, elastomers P1-1−P1-5 and P2-1−P2-5 exhibited cholesteric phase. With increasing the content of nematic crosslinking unit, T
g of the obtained elastomers revealed an increased tendency, and T
i of P1 series firstly increased then decreased, while T
i of P2 series decreased the mesomorphism of the corresponding elastomers when the content of nematic crosslinking unit was 12 mol.%. 相似文献
13.
Jian-she Hu Bao-yan Zhang Corresponding author Ke Sun Qian-yue Li 《Liquid crystals》2013,40(11):1267-1275
A series of new side chain cholesteric liquid crystalline elastomers (P-2–P-6) containing the nematic crosslinking monomer 4-(10-undecen-1-yloyloxy)benzoyl-4′-allyloxybenzoyl-p-benzenediol bisate (M-1) and the cholesteric monomer 4-cholesteryl 4-(10-undecen-1-yloyloxy)benzoate (M-2) were synthesized. The chemical structures of the monomers and elastomers obtained were confirmed by FTIR and 1H NMR spectroscopy. Their liquid crystalline properties and phase behaviour were investigated by differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction. The effect of the crosslinking units on phase behaviour is discussed. Elastomers containing less than 20?mol?% of the crosslinking units showed elasticity, reversible phase transitions and cholesteric Grandjean texture. The experimental results demonstrated that the glass transition and isotropization temperatures of P-2–P-6 increased with the increasing concentration of crosslinking unit M-1. 相似文献
14.
A series of new cholesteric side-chain liquid crystalline polymers were prepared containing cholesteric monomer and nonmesogenic
chiral monomer. All polymers were synthesized by graft polymerization using polymethylhydrosiloxane as backbone. The mesomorphic
properties were investigated by differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction measurements,
and temperature-changing solidistic optical rotation. The chemical structures of the monomers and polymers obtained were confirmed
by Fourier transform infrared and proton nuclear magnetic resonance spectra. M1 showed cholesteric phase during the heating and the cooling cycle. Polymer P1 were chiral smectic A phase, whereas P2–P7 were cholesteric phase. Experimental results demonstrated that nonmesogetic chiral moity offered the possibility of application
because of its lower glass-transition temperature, and the glass-transition temperatures and isotropization temperatures reduced,
and the ranges of the mesophase temperature changed abruptly at first and then smoothly with increasing the content of chiral
agent. 相似文献
15.
Fabiano V. Pereira Redouane Borsali Aloir A. Merlo Nadya P. Da Silveira Corresponding author 《Liquid crystals》2013,40(5):655-661
Small angle X-ray scattering was used to examine the new chiral side chain liquid crystalline polyacrylates (P4M and P11M) and their mixtures (2?wt?%) in the low molar mass nematogenics 4′-n-pentyl-4-cyanobiphenyl (5CB) and 4′-octyl-4-cyanobiphenyl (8CB). Complementary data were obtained by polarizing optical microscopy. In agreement with previous studies, the mesophases of the bulk polymers show a dependence on the aliphatic spacers linking the mesogenic units to the polymer backbone. Chiral nematic and smectic A1 phases were observed for the polyacrylates with four (P4M) and eleven (P11M) methylene units as spacers, respectively. In solution with 5CB and 8CB, P4M exhibits an injected smectic phase, whereas P11M maintains the smectic arrangement already observed in the bulk, with swollen smectic layers. In all the mixtures, layer stability was found to depend on the liquid crystal used as solvent, as well as on the temperature. At temperatures corresponding to the nematic 5CB and 8CB, the coexistence of two mesophases was observed in the mixtures. Moreover, with the liquid crystal solvents in the isotropic phase, microstructures suspended in the solvent matrix containing the liquid crystalline polymer in the smectic arrangement were detected. 相似文献
16.
Chiral monomer (M1 ), mesogenic and non-mesogenic crosslinking agents (C1 and C2 ), and the corresponding liquid crystalline elastomers (P1 and P2 series), have been synthesised. Their chemical structures have been characterised by Fourier transform infrared or 1H nuclear magnetic resonance and their phase behaviour investigated by differential scanning calorimetry, polarising optical miscoscopy, thermo-gravimetric analysis (TGA) and X-ray diffraction. The effect of the crosslinking unit on the phase behaviour of the elastomers has been studied. M1 showed a cholesteric oily streak and focal conic texture. C2 exhibited a nematic enantiotropic thread-like and schlieren texture, and a monotropic fan-shaped texture in the SA phase. Due to the introduction of the mesogenic crosslinking unit, elastomers, P2-1 ?P2-5 , exhibited a cholesteric phase, while elastomers, P1-1 ?P1-4 , derived from a non-mesogenic crosslinking unit, exhibit a SA phase. As the content of the crosslinking unit increased, the T g of the P1 series initially decreased and then increased, and the T i of the series decreased. In the P2 series the T g increased, but the T i initially increased and then decreased. TGA confirmed that all the elastomers had improved thermal stability. 相似文献
17.
A series of new chiral side-chain liquid crystalline polymers (P1–P7) have been synthesized with poly(methylhydrogeno)siloxane, two chiral liquid crystalline monomers, cholesteryl-4-allyloxybenzoate (M1) and cholesteryl 4-(10-undecylen-1-yloxy) benzoate (M2), and a nematic liquid crystalline monomer, 4-(trifluoromethyl)phenyl 4-(undec-10-enoyloxy)benzoate (M3). The chemical structures and liquid crystalline properties of the synthesized polymers have been investigated by FTIR, 1H-NMR, differential scanning calorimetry (DSC), polarizing optical microscopy (POM), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). All chiral polymers show wide mesophase temperature ranges and a high thermal stability with decomposition temperatures (T d) at 5 % weight loss greater than 300 °C. P1–P4 display a single cholesteric phase, but P5–P7 containing more fluorinated units show a smectic A (SA) phase besides a cholesteric phase. The optical properties of the polymers have been characterized by circular polarization spectra and optical rotation analysis. The cholesteric polymers P3 and P4 exhibit different colors at room temperature, and the color can remain over 24 months. The maximum reflection bands of polymers P1–P4 shift to long wavelength with increasing the content of M3 in the polymer systems. For P5–P7, the reflection wavelengths change sharply around the temperature of the SA–Ch phase transition. The specific rotation value of P2 smoothly decreases from ?8.2° to ?0.29° when it is heated, but the specific rotation value of polymer P7 changes from negative value to positive value on heating cycle. The optical properties of the polymers offer tremendous potential for various optical applications. 相似文献
18.
The synthesis is described of four new chiral liquid crystalline monomers (M2–M5 ) and their corresponding side‐chain homopolysiloxanes (P2–P5 ) containing menthyl groups. Chemical structures were characterised using FT‐IR or 1H NMR spectra, and specific optical rotations were evaluated with a polarimeter. The phase behaviour and mesomorphic properties of the new compounds were investigated by differential scanning calorimetry, thermogravimetric analysis, polarising optical microscopy, UV/visible/NIR spectrocopy and X‐ray diffraction. The monomers and homopolymers with more aryl segments showed noticeably lower specific optical rotation value. The monomers M2–M5 formed a cholesteric or blue phase when a flexible spacer was inserted between the rigid mesogenic core and the terminal menthyl groups by reducing the steric effect. M2–M5 revealed enantiotropic cholesteric phase. Moreover, M2 also exhibited a monotropic smectic A (SmA) phase, and M4 also exhibited a cubic blue phase on cooling. The selective reflection of light shifted to the long wavelength region with increasing rigidity of the mesogenic core for M2–M5 . P2–P5 exhibited SmA phases, and the mesogenic moieties were ordered in smectic orientation with their centres of gravity in planes. Melting or glass transition temperature and the clearing temperature increased, and the mesophase temperature range widened with increasing rigidity of the mesogenic core. 相似文献
19.
Rudolf Zentel 《Liquid crystals》2013,40(4):531-536
Abstract It is possible to untwist reversibly the helical superstructure of elastomers with cholesteric and chiral smectic C?phases by using strain. In that way a cholesteric structure can be transformed into a nematic structure and a chiral smectic C?into a smectic C structure. The latter case is especially interesting because a structure without a macroscopic polarization (chiral smectic C?) is transformed into one with a macroscopic polarization (smectic C like arrangement). 相似文献
20.
Jian‐She Hu Bao‐Yan Zhang Yan Guan Xiao‐Zhi He 《Journal of polymer science. Part A, Polymer chemistry》2004,42(20):5262-5270
New side‐chain cholesteric liquid‐crystalline elastomers containing cholesteryl 4‐allyloxybenzoate as cholesteric mesogenic units and biphenyl 4,4′‐bis(10‐undecen‐1‐ylenate) as smectic crosslinking units were synthesized. The chemical structures of the olefinic compounds and polymers obtained were confirmed by element analysis, Fourier transform infrared, proton nuclear magnetic resonance, and carbon‐13 nuclear magnetic resonance spectra. The mesogenic properties were investigated by differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy, and X‐ray diffraction measurements. The influence of the concentration of the crosslinking unit on the phase behavior of the elastomers was examined. The elastomers containing less than 17 mol % of the crosslinking units revealed elasticity, reversible mesomorphic phase transition, wider mesophase temperature ranges, and higher thermal stability. The experimental results demonstrated that the glass‐transition temperature, isotropization temperature, and mesophase temperature ranges decreased with an increasing concentation of the crosslinking unit. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5262–5270, 2004 相似文献