New thermotropic cubic mesophases

Demus, D.; Gloza, A.; Hartung, H.; Hauser, A.; Rapthel, I.; Wiegeleben, A.

doi:10.1002/crat.19810161225

Cited by 102 publications

(43 citation statements)

References 11 publications

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“…Figure 7.2 shows schematically the perceived molecular organization in some types of systems forming this phase. In most cases, the compound has a rodlike core with one or two terminal flexible chains -compounds 1 and compounds 4-8 [41][42][43][44] (Figure 7.3). The ANBC-n (compounds 1) form hydrogen-bonded dimers that effectively also act as rods [1,21].…”

Section: Double Gyroid Ia3d Phasementioning

confidence: 99%

“…It is interesting that while compounds 10, having a triethylammonium headgroup, display the Ia3d phase, analogous compounds with the smaller trimethylammonium group show only the Col h 11 (CH 2 ) 11 C 8 F 17 4(BABH-n) [41] 5 [6] 6 [42] 7 [43] 8 [44] 9 [48] 10 [49] 11 [50] 12 [46,47] phase. We shall return to this example in Section 7.3.4.…”

Section: Double Gyroid Ia3d Phasementioning

confidence: 99%

“…Similarly, a long series of BABH-n (4), originally prepared by Demus et al [41] was also synthesized and investigated by the same group [58]. The two series show similar intriguing phase behavior as a function of n, shown in Figure 7.6 [59].…”

Section: Double Gyroid Ia3d Phasementioning

confidence: 99%

See 2 more Smart Citations

Cubic and Other3DThermotropic Liquid Crystal Phases and Quasicrystals

Ungar

Liu

Zeng

2014

Handbook of Liquid Crystals

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Section: Double Gyroid Ia3d Phasementioning

confidence: 99%

Section: Double Gyroid Ia3d Phasementioning

confidence: 99%

See 1 more Smart Citation

Cubic and Other3DThermotropic Liquid Crystal Phases and Quasicrystals

Ungar

Liu

Zeng

2014

Handbook of Liquid Crystals

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“…Related to this flexibility of the oligo(ethylene oxide) chains, the importance of the ether linkage -O-between the core and chain part (which exists in the most of the complex mesophase forming molecules in Figure 1) could be pointed out. This 6 chains, and tetra-and hexa-catenar molecules; 17 classic cubic compounds ANBC, 18 BABH, 11 and rather new dichiral molecules. 12 In each molecule, the blue colored parts were assigned to the chain parts.…”

mentioning

confidence: 97%

“…3 Similar contrast can be found between compounds 6-10 and the comparable compound 9 which has the group -CHdN-NdCH-instead of the highly polar -CO-NH-NH-CO-in 6. 11 In this context, compounds 3 and 8 are exceptional among the other cubic LCs as these have rather low core-chain . For compound 3 with oligo(ethylene oxide) chains, the evaluations seems to be underestimated and shows its one aspect of limitation.…”

mentioning

confidence: 98%

Calamitic Liquid Crystals as Nanoscale Analogues of a Block Copolymer

et al. 2004

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The micro-segregation picture of a block copolymer was applied to a low molecular weight liquid crystal (LC) to clarify the similarities between them with respect to structured mesophase formation. Calamitic LC molecules were regarded as block compounds composed of a rigid anisometric core terminated by flexible chains. Then, the incompatibility parameter core-chain and volume fraction f core were considered analogous to AB and f A in A-B diblock copolymers. Fedors's method, which was originally used for polymers, was utilized to estimate core-chain and f core . We found good correspondence in the versus f phase diagram between block copolymers and block LCs.Liquid crystal (LC) materials that form complex nanostructured mesophases (e.g., cubic phase) have attracted increasing interest recently. 1 In these nonconventional LC materials, some individual molecular characteristics (e.g., hydrogenbonding, lateral dipole interactions) have been pointed out for the origin of such complex mesophase formations. 2,3 In addition, nanoscale segregation of incompatible molecular parts are considered to play an important role in their self-assembly. 4,5 Calamitic LC molecules can be regarded as block compounds composed of a rigid anisometric (mesogenic) core terminated by flexible chains. Polyphilic block molecules 1 consisting of a chemically incompatible core and chains, e.g., a hydrocarbon mesogenic core with oligo(ethylene oxide) chains, 6 siloxane chains, 5 or perfluoroalkyl chains 3 etc., have been found to form not only smectic but also columnar, cubic, and other threedimensionally structured mesophases. Such structured mesophases are popularly found in a block copolymer system, since even minor chemical differences are sufficient for such mesophase formation in large polymer molecules. 1 More precisely the parameters which govern these mesophase formations for A-B diblock copolymers are the total degree of polymerization N ) N A + N B , the Flory-Huggins parameter AB , and the volume fraction of the components f A . The Flory-Huggins parameter AB is a measure of the incompatibility between components A and B, and an order-disorder transition (e.g, formation of lamellar phase) occurs when AB N exceeds a critical value (∼10 at f ) 0.5). 7,4 Hence, low molecular weight LC molecules must possess a strong incompatibility between their different parts to form highly structured mesophases. 1 As the volume fraction f governs the interfacial curvature of the micro-segregated system, the phase diagram of the diblock copolymer can be represented in an f versus N diagram. 7 In this study, we try to adapt the f -N diagram approach to a structured mesophase forming a LC molecule to clarify the similarities to the copolymer. The Flory-Huggins parameter AB can be estimated according to the following equation:where δ A and δ B represent the Hildebrand solubility parameter and V R is a reference volume. 1 The solubility parameter δ is defined as the square root of the cohesive energy density and can be written as follows:where ∆E is the ...

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Introduction and Historical Development

Gray¹

1999

Physical Properties of Liquid Crystals

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New thermotropic cubic mesophases

Cited by 102 publications

References 11 publications

Cubic and Other3DThermotropic Liquid Crystal Phases and Quasicrystals

Cubic and Other3DThermotropic Liquid Crystal Phases and Quasicrystals

Calamitic Liquid Crystals as Nanoscale Analogues of a Block Copolymer

Introduction and Historical Development

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