Effect of Two Diferrent Mesogens on Liquid-Crystalline Properties of Chiral Side-Chain Liquid-Crystalline Polysiloxanes

2011 ◽  
Vol 415-417 ◽  
pp. 1395-1398
Author(s):  
Ji Wei Wang ◽  
Jun Qing Zi ◽  
Li Xian He ◽  
Guang Yong Chen ◽  
Yan Zhong Yang
Keyword(s):  
Liquid Crystalline ◽  
Proton Nuclear Magnetic Resonance ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Cholesteric Phase ◽  
Long Wavelength ◽  
Crystalline Polymers ◽  
Chemical Structures ◽  
Nuclear Magnetic Resonance Spectra ◽  
Temperature Ranges

Abstract. A series of liquid crystalline polysiloxanes were synthesized by cholesteric LC monomer and nematic LC monomer. The chemical structures and liquid-crystalline properties of the monomers and polymers were characterized by various experimental techniques including Fourier transform infrared (FTIR), proton nuclear magnetic resonance spectra (1H-NMR), differential scanning calorimetry (DSC), thermogravimetric analyses (TGA) , X-ray diffraction measurements (XRD) and polarizing optical microscopy (POM). All the liquid crystalline polymers showed liquid crystalline properties with wide mesophase temperature ranges. For the polymers bearing only of one nematic LC monomer, it showed nematic phase, while others showed cholesteric phase. With increase the content of nematic LC monomer in the polymers from P1 to P7, the glass transition temperature and the isotropic temperature increased on heating circles. Reflection spectra of cholesteric mesophase of the series of polymers showed that the reflected wavelength shifted to long wavelength with increase content of nematic LC monomer in the polymers in the polymer systems, suggesting that helical pitch (P) become long.

Chiral Liquid Crystal Polymers Containing Electron Donor- Acceptor Action-Synthesis and Characterization

2011 ◽  
Vol 284-286 ◽  
pp. 2284-2287
Author(s):  
Xiao Zhi He ◽  
Mei Tian ◽  
Yang Chen ◽  
Jing Zhao ◽  
Bao Yan Zhang
Keyword(s):  
Electron Donor ◽  
Liquid Crystalline ◽  
Proton Nuclear Magnetic Resonance ◽  
Liquid Crystal Polymers ◽  
Scanning Calorimetry ◽  
Cholesteric Phase ◽  
Chemical Structures ◽  
Heating And Cooling ◽  
Acceptor Group ◽  
Donor Acceptor

A series of new chiral side-chain liquid crystalline polymers with electron donor-acceptor action were prepared containing chiral monomer with donor group and nematic LC monomer with acceptor group. All polymers were synthesized by graft polymerization using polymethylhydro- siloxane as backbone. The mesomorphic properties were investigated by differential scanning calorimetry(DSC), polarizing optical microscopy(POM)，thermogravimetric analyses（TGA） and X-ray diffraction measurements(XRD). The chemical structures of monomers and polymers were confirmed by Fourier transform infrared (FTIR), proton nuclear magnetic resonance spectra(1H NMR and 13CNMR). M1 showed nematic phase and M2 turned out cholesteric phase on heating and cooling cycle. Polymers P3~P8 were cholesteric phase. Experimental results demonstrated that the glass transition temperatures and isotropization temperatures and the ranges of the mesophase temperature increased with increasing the content of chiral agent. All of the obtained polymers showed high thermal stability.

Synthesis and Properties of Side Chain Azobenzene Liquid Crystalline Polymers

2013 ◽  
Vol 781-784 ◽  
pp. 436-439
Author(s):  
Dan Shu Yao ◽  
Jun He ◽  
Hai Yan Wang ◽  
Mei Tian ◽  
Xiao Zhi He ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Graft Polymerization ◽  
Liquid Crystalline Polymers ◽  
Side Chain ◽  
Scanning Calorimetry ◽  
Crystalline Polymers ◽  
Chemical Structures ◽  
Thermogravimetric Analyzer ◽  
Temperature Ranges ◽  
Mesomorphic Properties

A series of new azobenzene side chain liquid crystalline polymers were synthesized by two different azo mesogen monomers, 4-((4-(ethoxycarbonyl) phenyl) diazenyl) phenyl 4-(allyloxy) benzoate (M1) and (4-((4-(ethoxycarbonyl) phenyl) diazenyl) phenoxy) methyl acetyl 4-(allyloxy) benzoate (M2). All polymers (P1~P8) were synthesized by graft polymerization using polymethyl hydrosiloxane as backbone. Their chemical structures were confirmed by FTIR and 1HNMR spectra. The mesomorphic properties and phase behavior were investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and thermogravimetric analyzer (TG) measurements. The results showed that P1~P8 exhibited thermotropic liquid crystalline properties and revealed nematic thread texture with wide mesophase temperature ranges. The temperatures when 5% weight loss occurred were higher than 305°C, which declared that the synthesized azobenzene liquid crystalline polymers had a high thermal stability.

scholarly journals Thermotropic Liquid-Crystalline and Light-Emitting Properties of Bis(4-aalkoxyphenyl) Viologen Bis(triflimide) Salts

Molecules ◽  
2020 ◽  
Vol 25 (10) ◽  
pp. 2435
Author(s):  
Pradip K. Bhowmik ◽  
Muhammed Kareem M. Al-Karawi ◽  
Shane T. Killarney ◽  
Erenz J. Dizon ◽  
Anthony Chang ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Variable Temperature ◽  
X Ray Diffraction ◽  
Metathesis Reaction ◽  
Scanning Calorimetry ◽  
Thermal Stabilities ◽  
Light Emitting ◽  
Chemical Structures ◽  
Nuclear Magnetic Resonance Spectra ◽  
13C Nuclear Magnetic Resonance

A series of bis(4-alkoxyphenyl) viologen bis(triflimide) salts with alkoxy chains of different lengths were synthesized by the metathesis reaction of respective bis(4-alkoxyphenyl) viologen dichloride salts, which were in turn prepared from the reaction of Zincke salt with the corresponding 4-n-alkoxyanilines, with lithium triflimide in methanol. Their chemical structures were characterized by 1H and 13C nuclear magnetic resonance spectra and elemental analysis. Their thermotropic liquid-crystalline (LC) properties were examined by differential scanning calorimetry, polarizing optical microscopy, and variable temperature X-ray diffraction. Salts with short length alkoxy chains had crystal-to-liquid transitions. Salts of intermediate length alkoxy chains showed both crystal-to-smectic A (SmA) transitions, Tms, and SmA-to-isotropic transitions, Tis. Those with longer length of alkoxy chains had relatively low Tms at which they formed the SmA phases that persisted up to the decomposition at high temperatures. As expected, all of them had excellent thermal stabilities in the temperature range of 330–370 °C. Their light-emitting properties in methanol were also included.

Optical Properties and Liquid-Crystalline Behaviors of Cyclosiloxane-Based Oligomer Films

2011 ◽  
Vol 391-392 ◽  
pp. 1179-1182
Author(s):  
Fan Bao Meng ◽  
Hong Mei Gao ◽  
Cui Zhi Zhu ◽  
Ri Li ◽  
Xiao Yan Lin
Keyword(s):  
Optical Properties ◽  
Glass Transition ◽  
Transition Temperature ◽  
Liquid Crystalline ◽  
Cholesteric Phase ◽  
Polymer Systems ◽  
Long Wavelength ◽  
Chemical Structures ◽  
Temperature Ranges ◽  
Synthesized Materials

A series of liquid crystalline (LC) oligomer films (IP-VP) were prepared by use of cyclo(tetramethylhydrogeno)siloxane (CTMHS), and two different cholesteric monomers that possess ortho- or para-substituted benzene. The chemical structures, liquid-crystalline properties and optical properties of the synthesized materials were characterized by various experimental techniques. All the samples showed cholesteric phase with very wide mesophase temperature ranges. From IP to VP, the glass transition temperature and the isotropic temperature decreased slightly with increase of C2PB component in the polymer systems. The maximum reflection bands shift to long wavelength from IP to VP, suggesting the helical pitch become longer with more ortho-substituted benzene in the polymer systems

Synthesis and Characterization of Bowl-Shaped Liquid Crystals with a Core of Calix[6]arene

2011 ◽  
Vol 396-398 ◽  
pp. 2202-2205
Author(s):  
Dan Shu Yao ◽  
Feng Li ◽  
Hao Jie Wang ◽  
Xiao Yun Li ◽  
Mei Tian ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Liquid Crystalline ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Cholesteric Phase ◽  
Chemical Structures ◽  
Liquid Crystalline Phases ◽  
Clearing Temperature ◽  
Mesomorphic Properties

A new kind of bowl-shaped liquid crystals were designed and synthesized by esterification. They used a calix[6]arene as central unit and ω- cholesteric alkyl diacid monoester as mesogenic arms. Their chemical structures were confirmed by FTIR and 1HNMR spectra, their mesomorphic properties and phase behavior were investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and X-Ray Diffraction (XRD) measurements. The results showed that the kind of calix[6]arene bowl-shaped liquid crystals N1-N3 exhibited broad range liquid crystalline phases at moderate temperature, and they displayed cholesteric phase focal-conic texture in liquid crystal states. With increasing the flexibility of monomers M1-M3, the melting point and the clearing temperature decreased in the macromolecules.

Synthesis and Properties of Thermotropic Liquid Crystalline Polyesters with Flexible Polymethylene Spacer

2010 ◽  
Vol 428-429 ◽  
pp. 126-131
Author(s):  
Wei Zhong Lu ◽  
Chun Wei ◽  
Qui Shan Gao
Keyword(s):  
Optical Microscopy ◽  
Liquid Crystalline ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Structure Morphology ◽  
Temperature Ranges ◽  
Ft Ir ◽  
Diffraction Peaks ◽  
Ubbelohde Viscometer

Polymethylene bis(p-hydroxybenzoates) were prepared from methyl p-hydroxybenzoate and different diols by melted transesterification reaction. Three liquid crystalline polyesters were synthesized from terephthaloyl dichloride and polymethylene bis(p-hydroxybenzoates). Its structure, morphology and properties were characterized by Ubbelohde viscometer, Fourier transform infrared spectroscopy (FT-IR), Differential scanning calorimetry (DSC), polarized optical microscopy (POM) with a hot stage, and wide-angle X-ray diffraction (WAXD). Results indicated that the intrinsic viscosities were between 0.088 and 0.210 dL/g. Optical microscopy showed that the TLCP has a highly threaded liquid crystalline texture and a high birefringent schlieren texture character of nematic phase and has wider mesophase temperature ranges for all polyesters. DSC analysis were found that the melting point (Tm), isotropic temperature (Ti) of TLCPs decreased and the temperature range of the liquid crystalline phase became wider with increased number of methylene spacers in the polyester. The WAXD results showed that TLCPs owned two strong diffraction peaks at 2θ near 19° and 23°.

Synthesis and Phase Behavior of Chiral Liquid Crystal Elastomers Containing Cholesteryl Group

2012 ◽  
Vol 554-556 ◽  
pp. 807-810 ◽  
Author(s):  
Ying Gang Jia ◽  
Kun Ming Song ◽  
Bao Yan Zhang
Keyword(s):  
Phase Behavior ◽  
Liquid Crystalline ◽  
Crosslinking Agent ◽  
Side Chain ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Selective Reflection ◽  
Cholesteric Phase ◽  
Liquid Crystal Elastomers ◽  
Cholesteric Liquid Crystalline

The synthesis of new side chain cholesteric liquid crystalline elastomers (ChLCEs) containing the cholesteric monomer M and the flexible non-mesogenic crosslinking agent C, is described. The selective reflection of light for M was characterized with UV/Visible/NIR. The phase behavior and mesomorphism were investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffraction (XRD). The effect of the content of crosslinking units on the phase behavior and mesomorphism of elastomers P1– P8is discussed. The ChLCEs exhibit elasticity, reversible phase transitions, and cholesteric Grandjean texture. The experimental results demonstrate that the glass transition temperature and isotropic temperature of ChLCEs decrease with increasing the content of crosslinking unit, but the cholesteric phase is not disturbed.

Chiral Liquid Crystalline Polymers Containing Isosorbide Groups

2013 ◽  
Vol 781-784 ◽  
pp. 403-406
Author(s):  
Mei Tian ◽  
Zhi Xin Xu ◽  
Li Gao ◽  
Dan Shu Yao ◽  
Xiao Zhi He ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Main Chain ◽  
Liquid Crystalline Polymers ◽  
Optical Microscope ◽  
Liquid Crystal Polymers ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Crystalline Polymers

A series of new main-chain liquid-crystal polymers (LCPs) were prepared from sebacoyl chloride (SD) and various amount of 4, 4-Dihydroxy-2, 2-dimethyl Benzalazine (DDBA) and isosorbide (ISO). The liquid crystal (LC) properties were investigated by polarized optical microscope (POM), differential scanning calorimetry (DSC) and X-ray diffraction measurements. P1 exhibited a typical nematic thread texture, which contains no ISO. P2-P7 are Sc* and N LCPs, which exhibited broken fan-shaped texture and droplet texture. The introduction of chiral units into the polymers led to a change of mesomorphase, as compared with P1.

Synthesis and phase behavior of chiral liquid crystalline polymeric networks derived from menthol

2012 ◽  
Vol 24 (8) ◽  
pp. 673-682 ◽  
Author(s):  
Ying-Gang Jia ◽  
Jian-She Hu ◽  
Dan Li ◽  
Qing-Bao Meng ◽  
Xia Zhang
Keyword(s):  
Phase Behavior ◽  
Near Infrared ◽  
Polymer Networks ◽  
Crosslinking Agent ◽  
Proton Nuclear Magnetic Resonance ◽  
Scanning Calorimetry ◽  
Excellent Thermal Stability ◽  
Cholesteric Phase ◽  
Temperature Range ◽  
Chemical Structures

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.

Optical properties of side-chain liquid crystal copolymers of monosubstituted cholesteryl itaconate and a non-chiral mesogen

1995 ◽  
Vol 73 (11) ◽  
pp. 1811-1817 ◽  
Author(s):  
J.M.G. Cowie ◽  
H.W. Hunter
Keyword(s):  
Itaconic Acid ◽  
Liquid Crystalline ◽  
Glassy State ◽  
Side Chain ◽  
Ultraviolet Region ◽  
Scanning Calorimetry ◽  
Selective Reflection ◽  
Cholesteric Phase ◽  
Crystalline Polymers ◽  
Derivatives Of

New mono- and disubstituted cholesteryl derivatives of itaconic acid have been prepared and their thermotropic liquid crystalline behaviour examined. The monosubstituted derivative has been homopolymerized, and also copolymerized with a non-chiral mesogen 4-cyanophenyl-4′-(6-acryloyl oxyhexyloxy) benzoate. Examination of the series of copolymers prepared, using differential scanning calorimetry and hot-stage polarizing microscopy, showed that when the content of the cholesteryl itaconate was high, both a smectic-A phase (SA) and a cholesteric phase (N*) were present. It was found that the SA phase could be eliminated by lowering the content of the cholesteryl itaconate in the copolymers, giving samples that displayed only the N* phase over a much wider temperature range. The samples in the N* phase also exhibited selective reflection of visible light that changed from short to long wavelengths as the samples were cooled from the isotropic melt. These colours can be locked into the glassy state of the polymer by quenching below the glass transition temperature, but only if the SA phase is absent. It was also noted that at high contents of the cholesteryl itaconate the selective reflection appears to occur in the ultraviolet region. Keywords: itaconic acid, copolymers, liquid crystalline polymers, cholesteric phases, selective reflection.

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