Rigid-Rod Polyesters with Flexible Side Chains. 6. Appearance of Hexagonal Columnar Phase as a Consequence of Microsegregation of Aromatic Main Chains and Aliphatic Side Chains

Watanabe, Junji; Sekine, Nobuhiro; Nematsu, Tokihiro; Sone, Masato; Kricheldorf, Hans R.

doi:10.1021/ma960342i

Cited by 58 publications

(55 citation statements)

References 20 publications

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“…21 The movement of crystalline segments is variably inhibited by the amorphous portion; thus, formation of various segregated structures is often observed from similar materials. The 'crystalline-crystalline' comb polymers, [22][23][24][25] especially those with aromatic main chain polymers, [26][27][28][29] are of interest because packing of the bulky aromatic polymer main chain can be changed by varying the crystallinity of side chains. As the first example, Kevlar, poly(p-phenylene terephthalamide), was functionalized with linear hydrocarbons of 3, 4, 7, 12 and 18 carbon atoms through metalation of poly(p-phenylene terephthalamide) using sodium hydride (degree of substitution (DS) was 86-99%, inherent viscosity (Z inh ) 0.06-0.14), and the packing mode was investigated for the resulting comb polymers, which were all amorphous except for the polymer with C 18 H 37 side chains.…”

Section: Introductionmentioning

confidence: 99%

Direct condensation polymerization of N-alkylated p-aminobenzoic acid and packing of rigid-rod main chains with flexible side chains

Shibasaki

Abe

Sato

et al. 2010

Polym J

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Direct condensation polymerization of N-alkylated p-aminobenzoic acid, in which methyl, propyl, butyl, pentyl, heptyl, octyl and heptadecyl substituents were used as the alkyl group, was performed using hexachloroethane, triphenylphosphine and pyridine as condensation reagents. Pale-yellow N-alkylated poly(p-benzamide) (PABA n ) polymers, where n is the number of carbon atoms of the alkyl side chain, were obtained in 46-87% yields with an inherent viscosity of 0.06-0.65 per 100 ml g À1 (conc. H 2 SO 4 , 30 1C). The structures of PABA n were identified using infrared, nuclear magnetic resonance and elemental analysis. PABA n with long alkyl side chains (n43) showed good solubility in chloroform, as well as conc. H 2 SO 4 and m-cresol. The glass transition temperature (T g ) of PABA n measured by differential scanning calorimetry gradually decreased with an increase in the length of the alkyl group. The endothermic peak corresponding to melting was observed for PABA n with n¼3, 4, 5 and 17 on DSC profiles. The wide-angle powder X-ray scattering of the polymer samples indicated that PABA n polymers with n¼0, 1, 3, 4, 5 and 17 were crystalline polymers. X-ray scattering profiles showed PABA n with n¼3, 4 and 5 crystallized in an orthorhombic lattice, whereas PABA 1 crystallized in a monoclinic lattice. PABA 17 crystallized in hexagonal packing at the long side chain with an interplanar spacing of 4.2 Å .

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Section: Introductionmentioning

confidence: 99%

Direct condensation polymerization of N-alkylated p-aminobenzoic acid and packing of rigid-rod main chains with flexible side chains

Shibasaki

Abe

Sato

et al. 2010

Polym J

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“…The driving force for an adoption of such a layered structure is a type of microphase separation of the aliphatic and aromatic domains, 2,5,6,12 and the liquid crystallinity is the results of a partial or total lack of positional order with respect to the main-chain packing within a layer and of the molten side chains between the layers. 12,13 In a previous paper, 17 we studied the thermotropic phase behavior and structures of the rigid-rod poly(pbiphenylene terephthalate) main chain with flexible dodecyloxy side chains attached to terephthalate moiety, It is interesting that this material forms a hexagonal columnar phase. This is the first example of a hexagonal columnar phase in this type of aromatic polyesters with flexible side chains.…”

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confidence: 99%

Rigid-Rod Polyesters with Flexible Side Chains IX. Phase Behavior Including Nematic, Layered, and Hexagonal Columnar Phases in Poly(p-biphenylene terephthalate) with Alkoxy Side Chains

Sekine

Sone

et al. 2002

Polym J

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ABSTRACT:In this study we prepared a series of poly(p-biphenylene terephthalate) with alkoxy side chains attached to terephthalate moiety. The carbon number of alkoxy side chains, n, is ranged from 8 to 18. These polymers exhibited well-defined thermotropic phase behavior with a nematic phase in the higher temperature region and two ordered mesophases in the lower temperature region. One of the lower temperature mesophases was found to be a hexagonal columnar phase in the polymers with smaller values of n (8 to 12), while the other is the layered mesophase preferentially formed from the polymer with n = 18. In the polymers with n = 13, 14, and 16, the columnar and layered mesophases coexist. In these intermediate polymers, the relative amount of the layered phase to the columnar phase increases with the increase of n. Further, it increases when the mesophase temperature decreases, indicating that the layered phase is thermodynamically lower temperature mesophase than the columnar one. While the layered phase is occasionally observed in this kind of polymers with long alkyl side chains, the columnar phase is new and interesting since many chains are included in its hexagonal unit cell. The number of chains increases from 7 to 12 with an increase of n from 8 to 14. To achieve the reasonable packing of the aromatic main chains, we proposed the special hexagonal structure where the fully extended main chains are closely packed with lateral spacing of around 4.5 Å to form a honeycombed network and the molten side chains are accommodated within a resulting cylindrical domain.KEY WORDS Aromatic Polyesters / Alkyl Side Chain / Liquid Crystal / Hexagonal Columnar Phase / Layered Phase / There have been several recent reports in the literature on thermotropic phase behavior of the rigid-rod polymers with long flexible alkyl side chains. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] The most interesting property of these materials is an ability to form layered structures in crystals and liquid crystals when the alkyl side chains reach a critical length. The layered mesophases are characterized by a closed packing of the rigid-rod main chains into layers with the molten side chains occupying a space between the layers. The driving force for an adoption of such a layered structure is a type of microphase separation of the aliphatic and aromatic domains, 2,5,6,12 and the liquid crystallinity is the results of a partial or total lack of positional order with respect to the main-chain packing within a layer and of the molten side chains between the layers. 12,13 In a previous paper, 17 we studied the thermotropic phase behavior and structures of the rigid-rod poly(pbiphenylene terephthalate) main chain with flexible dodecyloxy side chains attached to terephthalate moiety, It is interesting that this material forms a hexagonal columnar phase. This is the first example of a hexagonal columnar phase in this type of aromatic polyesters with flexible side chains. Although several examples of the columnar phase have so far ...

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“…layers in the lamellar phase and walls in the inverted cylindrical phase are two polymer backbones thick. Experimentally both double [45] and single wall [12] morphologies have been observed. Analysis of the dihedral angles between the sidechains shows that all the sidechains for a given polymer lie on the same side of the backbone.…”

Section: Resultsmentioning

confidence: 82%

“…Poly(p-phenylene) derivatives have also been shown to form lamellar phases for sufficiently long flexible chains [10]. As well as lamellar phases, cylindrical phases have been observed in polyfluorene derivatives [11], while lamellar and inverted cylindrical phases have been observed for rigid-rod polyesters [12,13]. Flory theory [14] has been used to study the phase behaviour of hairy rods, primarily to study the nematic-isotropic transition in these systems [15,16].…”

Section: Introductionmentioning

confidence: 99%

Molecular structure and phase behaviour of hairy-rod polymers

Cheung

Troisi

2009

Phys. Chem. Chem. Phys.

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Using dissipative particle dynamics simulations the relationship between molecular architecture and phase behaviour in model hairy-rod polymers is studied. In agreement with experimental and theoretical studies the phase behaviour is controlled by changes to the molecular structure, particularly the sidechain length and density, and the molecular interactions. For dense sidechains a lamellar structure is found, which becomes an inverted cylindrical phase when the sidechain density is lowered. The ordered phases become more stable on increasing sidechain length and on increasing the repulsion strength between the backbone and sidechains. In the absence of torsional potentials the structures are double-walled, i.e. layers are two polymer backbones thick, while single-walled structures are observed for polymers with torsional potentials

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Rigid-Rod Polyesters with Flexible Side Chains. 6. Appearance of Hexagonal Columnar Phase as a Consequence of Microsegregation of Aromatic Main Chains and Aliphatic Side Chains

Cited by 58 publications

References 20 publications

Direct condensation polymerization of N-alkylated p-aminobenzoic acid and packing of rigid-rod main chains with flexible side chains

Direct condensation polymerization of N-alkylated p-aminobenzoic acid and packing of rigid-rod main chains with flexible side chains

Rigid-Rod Polyesters with Flexible Side Chains IX. Phase Behavior Including Nematic, Layered, and Hexagonal Columnar Phases in Poly(p-biphenylene terephthalate) with Alkoxy Side Chains

Molecular structure and phase behaviour of hairy-rod polymers

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