Synthesis and Physical Properties of π -Conjugated Polymers Containing Mesogenic Group

1996 ◽  
Vol 425 ◽  
Author(s):  
Y. Watanabe ◽  
N. Koide
Keyword(s):  
Aromatic Compound ◽  
Liquid Crystalline ◽  
Oxidation Potential ◽  
Side Chain ◽  
Mesogenic Group ◽  
Scanning Calorimetry ◽  
Polymer Backbone ◽  
Crystalline Polymers ◽  
Lower Oxidation ◽  
Chain Type

AbstractNovel side chain type liquid crystalline polymers, polythiophene and poly(aryleneethynylene) [PAE], containing a mesogenic group in the side chain were synthesized. Polythiophene derivatives were obtained by dehalogenative polycondensation with zero-valence nickel complex under mild condition. PAE type polymers were obtained by coupling dihalo aromatic compound with diethynyl aromatic compound. Their thermal properties were examined by differential scanning calorimetry, optical microscopy and X-ray diffractometry. All polymers exhibited a smectic or nematic mesophase depending upon the polymer backbone and pendant mesogenic group. Polythiophene derivatives exhibited electrochemical activity. Annealing polythiophene derivatives led to a lower oxidation potential and a higher conductivity. The degree of the orientation of the polymer backbone was supported by polarized UV-vis measurement. An effective conjugated length became longer by introducing thiophene rings into the polymer backbone. A high quantum yield of fluorescence was observed for PAE type polymers.

The Effect of Hydrogen Bonding on the Mesomorphic Properties for Side Chain Type Liquid Crystalline Polyurethanes

1996 ◽  
Vol 425 ◽  
Author(s):  
T. Mihara ◽  
N. Koide
Keyword(s):  
Hydrogen Bonding ◽  
Liquid Crystalline ◽  
Side Chain ◽  
Flexible Chain ◽  
Remarkable Change ◽  
Polymer Backbone ◽  
Phase Transition Temperatures ◽  
Ft Ir ◽  
Mesomorphic Properties ◽  
Chain Type

AbstractMesomorphic properties and temperature dependence of the hydrogen bonding between urethane bonds (H-bonding) for side chain type liquid crystalline polyurethane(SLCPU)s were studied by thermally controlled FT-IR spectroscopy. A remarkable change in the strength of H-bonding for SLCPUs with a flexible chain in the polymer backbone(flexible SLCPUs) was displayed near the phase transition temperatures, while small changes in the strength of H-bonding for SLCPUs with a rigid moiety in the polymer backbone(rigid SLCPUs) was influenced by a mesogenic group in the side chain and the flexible chain length in the polymer backbone. Furthermore, in order to study the influence of H-bonding in rigid SLCPUs, polyurethane derivatives with methyl group were synthesized replacing hydrogen in urethane bonds. No mesomorphic properties for polyurethane derivatives obtained were exhibited. It was concluded that H-bonding played an important role to exhibit mesomorphic properties of rigid SLCPUs.

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.

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.

Side chain liquid crystalline polymers containing siloxane spacer: 7. Syntheses and properties of polyimides and polyamides containing a mesogenic side chain connected with a disiloxane linkage

1995 ◽  
Vol 7 (3) ◽  
pp. 255-266 ◽  
Author(s):  
Yu Nagase ◽  
Yuriko Takamura ◽  
Eiichi Akiyama
Keyword(s):  
Liquid Crystalline ◽  
Main Chain ◽  
Catalytic Reduction ◽  
Side Chain ◽  
Mesogenic Group ◽  
Structural Effects ◽  
Siloxane Bond ◽  
Crystalline Polymers ◽  
Aliphatic Group ◽  
Smectic Mesophase

Preparations of polyimides and polyamides containing a mesogenic group in the side chain connected with a siloxane bond in the spacer component were carried out. A 3,5-diaminobenzyloxy-type monomer having a mesogen consisting of a p'-substituted biphenyl benzoate group was prepared by means of hydrosilylation of 1-[3-43,5-dinitrobenzyloxy)propyl]-1,1,3,3-tetramethyldisiloxane with a mesogenic allyloxy compound, followed by catalytic reduction of the two nitro groups. The polyimides were synthesized by polycondensation of the diamine monomers with 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), followed by chemical imidization. The polyamides were also synthesized by polycondensation of the diamine monomers with dicarboxylic dichloride compounds, i.e., terephthaloyl dichloride, oxalyl dichloride, malonyl dichlonride, succinyl dichloride, glutaryI dichloride, adipoyl dichloride, pimeloyI dichloride and azelaoyl dichloride. The structural effects on the thermal properties of the polymers were investigated. The obtained polyamides having an aliphatic group in the main chain exhibited an enantiotropic smectic mesophase at around 100-150C, while no mesophase was observed for the polyimides and a polyamide having an aromatic backbone.

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.

Liquid crystalline polymers

2004 ◽  
Author(s):  
Sangdil I. Patel ◽  
Fred J. Davis
Keyword(s):  
Liquid Crystalline ◽  
Main Chain ◽  
Liquid Crystalline Polymers ◽  
Phase Behaviour ◽  
Side Chain ◽  
Polymer Backbone ◽  
Crystalline Materials ◽  
Crystalline Polymers ◽  
Anisotropic Behaviour ◽  
Liquid Crystalline Materials

The idea of combining the anisotropic behaviour of liquid crystalline materials with the properties of macromolecular systems was first suggested by Onsanger and subsequently Flory. The actual realization that such systems could exist came from studies of natural polymers such as the tobacco mosaic virus. Interest in these systems intensified with the development of highstrength systems, based on rigid-rod systems, notably the aramid fibres, however, liquid crystallinity in such systems occurs only at high temperatures, usually close to the decomposition point of the polymer. It was only in the late 1970s that the design criteria for liquid crystalline polymers became apparent, the secret being largely in the decoupling of the rigid aromatic groups which give rise to the anisotropic behaviour. As a result of these ideas two classifications of liquid crystalline materials were described. Main-chain liquid crystalline polymers, are those in which rigid aromatic molecules form part of the polymer backbone, either as a continuous chain or separated by a series of methylene groups in order to lower temperature at which liquid crystalline phase behaviour is observed. Side-chain systems resemble the comb-like systems studied by Shibaev and Plate, and have the rigid aromatic groups attached as a side-chain. In general, the monomer systems required for main-chain liquid crystalline polymers are relatively simple; synthetically these systems are prepared by step-growth methods and the main challenge is often maintaining sufficient solubility to allow suitable chain-lengths to be grown (an example of how such problems might be overcome is given in Chapter 4). Side-chain systems tend to be produced from more complex structural sub-units, and may be produced either by polymerization of the appropriate monomer or by functionalization of a preformed polymer backbone. Examples of both approaches are given in this chapter. From a practical viewpoint, the advantage of side-chain systems is that they tend to be much more soluble in common organic solvents and also that thermal phase transitions occur at reasonable temperatures (reasonable being well below the temperature at which the polymer decomposes). A further advantage of such side-chain systems is that the phase behaviour can be effectively tuned through the chemical modifications of the three components, namely the side-group, the flexible coupling chain and the polymer backbone.

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