X-ray investigation of combined main-chain/side-chain liquid-crystalline polymers

Diele, Siegmar; Naumann, Matthias; Kuschel, Frank; Reck, Bernd; Ringsdorf, Helmut

doi:10.1080/02678299008036753

Cited by 32 publications

(19 citation statements)

References 17 publications

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“…Compared with the corresponding main-chain and side-chain LCPs, the mesophase temperature range of MCSCLCPs is surprisingly broad; this is attributed to the synergistic stabilization of the LC phase between the main-chain and side-chain mesogenic units (Endres et al 1990). Later, the synthesis and the correlation between the liquid-crystalline behavior and structural variations of MCSCLCPs have been extensively reported (Watanabe and Tominaga 1993;Reck et al 1989;Diele et al 1990; Kapitza and Zentel 1991;Pakula and Zentel 1991;Ge et al 1997;Piao et al 1997;Chen et al 1999;Ruan et al 2002Ruan et al , 2006Schaefer et al 2006). Traditionally, there are two types of main chain as the backbone of MCSCLCPs: one is non-rigid in character containing flexible spacers (Reck and Ringsdorf 1985;Zentel 1988, 1991;Kremer et al 1989;Poths et al 1991;Zentel and Brehmer 1996;Joo et al 2000;Zhou and Han 2005;Huang and Han 2006) and the other is rigid in nature without any flexible spacers (Ge et al 1997;Piao et al 1997;Lee et al 1999;Cha et al 2001;Ruan et al 2002).…”

Section: Introductionmentioning

confidence: 98%

Design, synthesis, and characterization of a combined main-chain/side-chain liquid-crystalline polymer based on ethyl cellulose

Xie

Xiao

et al. 2010

Cellulose

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A novel combined main-chain/side-chain liquid-crystalline polymer based on an ethyl cellulose main chain containing azobenzene mesogens (AzoEC) was successfully synthesized. Molecular characterization of the resulting polymers with different degrees of substitution (DS) was performed with proton nuclear magnetic resonance ( 1 H NMR), Fourier-transform infrared spectroscopy (FTIR), and gel permeation chromatography (GPC). Thermal stability was investigated by thermogravimetric analysis (TGA). The phase transitions and liquid-crystalline behavior of these polymers were investigated by differential-scanning calorimetry (DSC), polarized optical microscopy (POM), and wide-angle X-ray diffraction (WAXD). The results indicate that DS has substantial effect on the liquid-crystalline behavior of these polymers. AzoEC with low DS only shows the cholesteric phase similar to ethyl cellulose (EC). However, when DS increases to a specific value, AzoEC begins to show fascinating supramolecular structures. The supramolecular structure of AzoEC with maximum DS consisted of a large-scale ordered lamellar structure formed by EC main chains and a small-scale ordered structure formed by azobenzene mesogens.

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Section: Introductionmentioning

confidence: 98%

Design, synthesis, and characterization of a combined main-chain/side-chain liquid-crystalline polymer based on ethyl cellulose

Xie

Xiao

et al. 2010

Cellulose

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“…It has been reported that multiple-step process from smectic to isotropic transitions occurs in combined-type polymalonates having the methoxyazobenzene unit by Ringsdorf et al 2,21 In very recent years, polyketones bearing side-chain azobenzene unit were disclosed to Relationships between Structures and Liquid Crystalline and Optical Properties in Combined-type Copolyisophthalates form smectic LC phase. 29 In this way, many sidechain or combined-type polymers having the azobenzene moieties exhibit smectic phases.…”

Section: Mesomorphic Propertiesmentioning

confidence: 99%

“…2, 21 Kodaira et al disclosed that copolymalonates with the sidechain nitroazobenzene and methoxybiphenyl units have wider temperature ranges of nematic phase than the homopolymalonates, where electron donor-acceptor interaction between the mesogens with electron-donating and electron-withdrawing groups acts an important role. 22 In addition, copolymers containing monomer units with specific interaction such the electron donor-acceptor interaction have been found to form smectic mesophases.…”

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confidence: 99%

Relationships between Structures and Liquid Crystalline and Optical Properties in Combined-type Copolyisophthalates Having Nitro- and Methoxyazobenzene Units and Aliphatic Spacers in the Side Chain

Sato

Mizoi

2004

Polym J

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ABSTRACT:Combined-type thermotropic liquid crystalline (LC) homo-and copolyisophthalates having nitroand methoxyazobenzene units and three aliphatic spacers (hexamethylene, octamethylene and decamethylene) in the side chain and biphenyl unit in the main chain were prepared by melt polycondensation and relationships between polymer structures and LC and optical properties were discussed. Differential scanning calorimetry (DSC) measurements, optical texture observations using polarizing microscopy and powder X-Ray analyses indicated that the homopolyisophtalates with the nitroazobenzene unit form highly ordered smectic E phase and the other homo-and copolymers show less ordered smectic B or smectic C phase. The temperature ranges of smectic LC phases in the polymers decreased with increasing the methoxyazobenzene content. In these polymers, specific interaction such as electron donor-acceptor interaction between the nitro-and the methoxyazobenzene units plays no role in the formation and the stabilization of smectic LC phases. All the polymers displayed UV-vis absorption peak maxima on the basis of the azobenzenes or the biphenyl in solutions and in films, but no fluorescent properties were found, probably due to intraand intermolecular quenching. [DOI 10.1295/polymj.36.607] KEY WORDS Combined-type Polyisophthalate / Melt Polycondensation / Liquid Crystalline Property / Optical Property / Azobenzene / Biphenyl / Differential Scanning Calorimetry / Smectic Phase / It is well known that there are three types of polymers in thermotropic liquid crystalline (LC) polymers: (1) main-chain polymers, (2) side-chain polymers and (3) combined-type polymers.1 The combined-type polymers, which have calamitic mesogens such as biphenyl, diphenyls and azobenzenes both in the side and the main chains, tend to have broader LC temperature ranges of mesophases than the parent main-chain and side-chain polymers and to show nematic phase together with smectic phases owing to the synergy effect of mesogens in the side and the main chains.2 Researches on the combined-type LC polymers are still not adequate, 3 although a number of literatures on chemical and physical properties of main-chain and side-chain LC polymers have been reported. 4,5 On the other hand, side-chain azobenzene-containing polymers have attracted much attention because of potentials as polymers for photonics applications 7-16 in addition to LC properties. 4,17 The azobenzene derivatives have been known for displaying no photoluminescence (PL), but it has been found that the azobenzene derivatives 18 and poly(p-phenylenevinylene)s (PPV) 19 having side-chain methoxyazobenzene unit emit PL light, having very low quantum yields. 18 Our previous paper 20 has described that novel combined-type semi-rigid homopolyisophthalates having biphenyl or 2,5-diphenyl-1,3,4-thiadiazole (DTD) unit in the main chains and azobenzene moieties in the side chains are synthesized by melt polycondensation and that most of them form stable smectic LC (B, C and E) phases without showing nema...

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“…These polymers are commonly called main chain liquid crystalline polymers (LCPs). [1][2][3][4][5][6][7] In contrast, the side chain LCPs [8][9][10][11][12][13] contain the mesogenic units in the side branches or as pendants. Many papers [1][2][3][4][5][6][7] have been published during the past quarter of a century on the structure-property relationships of main chain LCPs.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Liquid Crystalline Properties of Hyperbranched Aromatic Polyesters Consisting of Azoxybenzene Mesogens and Polymethylene Spacers

Park¹,

Lee²,

Jin³

2002

Bulletin of the Korean Chemical Society

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A new series of hyperbranched aromatic polyesters containing azoxybenzene mesogens and polymethylene spacers were prepared by polymerizing AB 2 type monomers that have the isophthaloyl dicarboxylic acid terminal at one end and the p-oxyphenol terminal at the other end. The monomers contain a built-in azoxybenzene mesogen that is linked to the terminal groups through polymethylene spacers. The polyesters prepared were characterized by solution viscosity, differential scanning calorimetry, X-ray diffractometry and polarizing microscopy. All of the polyesters were found to be thermotropic (nematic). Their glass-transition temperatures and mesophase temperature ranges were very sensitive to the length of the two spacers existing in the repeating unit. The degree of branching of one of the polyesters was determined by the NMR spectroscopy and found to be 0.56.

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X-ray investigation of combined main-chain/side-chain liquid-crystalline polymers

Cited by 32 publications

References 17 publications

Design, synthesis, and characterization of a combined main-chain/side-chain liquid-crystalline polymer based on ethyl cellulose

Design, synthesis, and characterization of a combined main-chain/side-chain liquid-crystalline polymer based on ethyl cellulose

Relationships between Structures and Liquid Crystalline and Optical Properties in Combined-type Copolyisophthalates Having Nitro- and Methoxyazobenzene Units and Aliphatic Spacers in the Side Chain

Synthesis and Liquid Crystalline Properties of Hyperbranched Aromatic Polyesters Consisting of Azoxybenzene Mesogens and Polymethylene Spacers

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