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.

A comparative study of side chain liquid crystalline polymers and their monomers designed for nonlinear optical applications

1991 ◽  
Vol 6 (3) ◽  
pp. 604-609 ◽  
Author(s):  
R.B. Findlay ◽  
T.J. Lemmon ◽  
A.H. Windle
Keyword(s):  
Transition Temperature ◽  
Liquid Crystalline ◽  
Nonlinear Optical ◽  
Liquid Crystalline Polymers ◽  
Significant Degree ◽  
Side Chain ◽  
Crystalline Polymers ◽  
Chemical Structures ◽  
Optical Applications ◽  
Nonlinear Optical Applications

Characterizations of side chain liquid crystalline polymers and their monomers point toward chemical structures and processing techniques which optimize their suitability for nonlinear optical applications. Polymers with methacrylate backbones and nitrostilbene or nitrobiphenyl side groups are studied; they tend to form smectic phases, but no solid crystallinity. By copolymerizing with nonmesogenic backbone units, the smectic-isotropic transition temperature can be controlled and may fall below the glass transition temperature. There is evidence for a significant degree of pretransitional alignment due to the surface fields, and mesogen ordering perpendicular to flow-induced backbone alignment. Very rapid cooling can suppress the highly scattering polydomain smectic phase.

Synthesis of Ferroelectric Liquid Crystalline Polymers by Ring Opening Polymerization

1996 ◽  
Vol 425 ◽  
Author(s):  
C. S. Hsu ◽  
C. J. Lee
Keyword(s):  
Ring Opening ◽  
Liquid Crystalline ◽  
Liquid Crystalline Polymers ◽  
Ring Opening Polymerization ◽  
Side Chain ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Crystalline Polymers ◽  
Smectic A ◽  
Smectic C

AbstractThe synthesis of two series of side-chain liquid crystalline polyoxetanes and polyoxiranes containing 4-alkanyloxybiphenyl-4′ -yl (2S,3S)-2-chloro-3-methylvalerate side groups is presented. Differential scanning calorimetry, polarizing optical microscopy, and X-ray diffractometry reveal smectic mesomorphism for all obtained polymers. Most of the prepared polyoxetanes present smectic A and chiral smectic C phases. The polyoxetane containing tweleve methylene units in the spacer is the only one showing two enantiotropic smectic A and B phases. All of the obtained polyoxiranes display two enantiotropic smectic A and B phases. Although the polyoxetane and polyoxirane backbones are more flexible than the polymethacrylate backbone, side-chain crystallization do not occur in any of the synthesized polymers.

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.

Synthesis and Mesomorphism of Novel Star-Shaped Liquid Crystals Containing Donor-Acceptor Groups

2013 ◽  
Vol 395-396 ◽  
pp. 72-75 ◽  
Author(s):  
Dan Shu Yao ◽  
Jun He ◽  
Guo Hua Li ◽  
Qian Xu ◽  
Ying Gang Jia ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Phase Behavior ◽  
Liquid Crystalline ◽  
Scanning Calorimetry ◽  
H Nmr ◽  
Chemical Structures ◽  
Thermogravimetric Analyzer ◽  
Liquid Crystalline Phases ◽  
Temperature Ranges ◽  
Donor Acceptor

A new class of three-armed star-shaped liquid crystals 5a-5d were synthesized, they used 1,3,5-trihydroxybenzene as a core, ω-[4-(p-ethoxybenzoloxy) phenoxycarbonyalkyl acid (3a, 3b) and ω-[4-(p-nitrobenzoloxy) phenoxycarbonyalkyl acid (3c, 3d) as mesogenic arms. Their chemical structures were confirmed by FTIR and 1H NMR 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 the three-armed star-shaped liquid crystals exhibited a broad range of liquid crystalline phases at moderate temperature. The mesogenic arm structures obviously affected the phase behavior. As the intermedius alkyl chain of the star-shaped compounds lengthened (from n=4 to n=8), their melting points decreased but mesomorphic temperature ranges increased. The temperatures when 5% weight loss occurred (td) were higher than 300°C, which revealed that the synthesized three-armed liquid crystals had a high thermal stability. Threadlike, droplet and schlieren texture, typical of nematic phase can be observed in the liquid crystalline state during heating or cooling process.

Microstructural Control in Side Chain Polymers for Optical Applications

1989 ◽  
Vol 175 ◽  
Author(s):  
Rob Findlay ◽  
Tim Lemmon ◽  
Alan Windle
Keyword(s):  
Liquid Crystalline ◽  
Liquid Crystalline Polymers ◽  
Side Chain ◽  
X Ray ◽  
Crystalline Polymers ◽  
Chemical Structures ◽  
Polarised Light ◽  
Optical Applications ◽  
Processing Techniques ◽  
Microstructural Control

AbstractCharacterisations of side chain liquid crystalline polymers point towards chemical structures and processing techniques which optimise their suitablility for non-linear optical (NLO) applications. Techniques used are thermal analysis, X-ray and hotstage polarised light microscopy (orthoscopic and conoscopic).

A New Series of Two-Ring-Based Side Chain Liquid Crystalline Polymers: Synthesis and Mesophase Characterization

2013 ◽  
Vol 66 (6) ◽  
pp. 667 ◽  
Author(s):  
Goddeti Siva Mohan Reddy ◽  
Tanneru Narasimhaswamy ◽  
Jarugala Jayaramudu ◽  
Emmanuel Rotimi Sadiku ◽  
Konduru Mohana Raju ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Variable Temperature ◽  
Liquid Crystalline Polymers ◽  
Side Chain ◽  
Scanning Calorimetry ◽  
Crystalline Polymers ◽  
Molecular Weights ◽  
Smectic C ◽  
Phenyl Rings ◽  
Alkoxy Groups

A new series of side chain liquid crystalline polymers containing a core, a butamethylenoxy spacer, ester groups, and terminal alkoxy groups were synthesised and their structures were confirmed. The core was constructed with two phenyl rings and an ester linking unit. All the polymers were characterised by hot-stage polarising optical microscopy, differential scanning calorimetry, variable temperature X-ray diffraction, thermogravimetric analysis, and gel permeation chromato-graphy. The polymers were found to be liquid crystalline. The nematic and smectic A (SA) phases were observed for the homologues with short-terminal chains (C2 and C6), whereas the homologues with longer chains (C8 to C12) exhibited a smectic C phase. The thermal stability of the polymers was found to be in the range of 293 to 326°C and the molecular weights of the polymers were found to vary from 6 × 103 to 1.3 × 104.

scholarly journals Phase Transitions of Side Chain Liquid Crystalline Polymers Having a Terminal Alkyl Chain.

1993 ◽  
Vol 50 (9) ◽  
pp. 687-691 ◽  
Author(s):  
Seiji UJIIE ◽  
Tamami FUKUI ◽  
Kazuko HIGAKI ◽  
Satoshi TAKAHASHI ◽  
Kazuyoshi IIMURA
Keyword(s):  
Phase Transitions ◽  
Liquid Crystalline ◽  
Alkyl Chain ◽  
Liquid Crystalline Polymers ◽  
Side Chain ◽  
Crystalline Polymers
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