Columnar discotics in confined geometries

Kopitzke, Jörg; Wendorff, Joachim H.; Glüsen, Andreas

doi:10.1080/026782900202499

Cited by 29 publications

(24 citation statements)

References 25 publications

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“…This is unexpected, because in a confining geometry the formation of this highly ordered phase is commonly suppressed. Even at room temperature confined LCs of the triphenylene type usually consist of the Col ho phase, which occurs in the bulk only at temperatures above 168 C. [32,48] …”

Section: Full Papermentioning

confidence: 99%

Morphology of Polymer/Liquid‐Crystal Nanotubes: Influence of Confinement

Steinhart

Murano

Schaper

et al. 2005

Adv Funct Materials

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Polymer/liquid‐crystal (LC) tubes consisting of an approximately 30 nm thick poly(methyl methacrylate) (PMMA) layer on the outside and a 5 to 10 nm thick discotic liquid‐crystalline layer on the inside of the tube walls have been prepared by wetting ordered porous alumina templates with a pore diameter of 400 nm. Decreasing the pore diameter to 60 nm results in a confinement‐induced transition from a wetting state to a non‐wetting state, and solid rods with a sequential morphology are obtained. The texture of the mesophase depends on the morphology type and the thermal history. Under certain conditions the LC mesophase exhibits a dominant, well‐ordered planar texture where the discotic columns are aligned with the long axes of the tubes. The controlled generation of one‐dimensional nano‐objects possessing mesoscopic fine structures and intrinsic anisotropy should be the first step towards a rational design of miniaturized building blocks.

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Section: Full Papermentioning

confidence: 99%

Morphology of Polymer/Liquid‐Crystal Nanotubes: Influence of Confinement

Steinhart

Murano

Schaper

et al. 2005

Adv Funct Materials

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“…This competition between surface anchoring and tendency to form rigid, hexagonal columnar phases has turned out to be decisive for the formation of either axial or radial or circular concentric arrangements of the columns in cylindrical nano confinement [27][28][29][30][31][32][48][49][50]. For edge-on anchoring Zhang et.…”

Section: Discussionmentioning

confidence: 99%

High-resolution dielectric study reveals pore-size-dependent orientational order of a discotic liquid crystal confined in tubular nanopores

et al. 2015

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We report a high-resolution dielectric study on a pyrene-based discotic liquid crystal (DLC) in the bulk state and confined in parallel tubular nanopores of monolithic silica and alumina membranes. The positive dielectric anisotropy of the DLC molecule at low frequencies (in the quasi-static case) allows us to explore the thermotropic collective orientational order. A face-on arrangement of the molecular discs on the pore walls and a corresponding radial arrangement of the molecules is found. In contrast to the bulk, the isotropic-to-columnar transition of the confined DLC is continuous, shifts with decreasing pore diameter to lower temperatures and exhibits a pronounced hysteresis between cooling and heating. These findings corroborate conclusions from previous neutron and Xray scattering experiments as well as optical birefringence measurements. Our study also indicates that the relative simple dielectric technique presented here is a quite efficient method in order to study the thermotropic orientational order of DLC based nanocomposites.

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“…In fact, double peaks have been reported for low molar mass triphenylene systems in the literature and assigned to a rectangular packing. [19,31] Yet the two peaks were in these cases more narrowly spaced but in any case using the program DataSqueeze one is able to fit the diffraction diagram to a columnar rectangular or centered columnar rectangular phase. Nevertheless, additional structural investigations are required for a more detailed structure assignment.…”

Section: Molecular Structurementioning

confidence: 99%

“…[17,18] Disordered narrow channels in porous glasses, for instance, were found not only to cause modifications of the type of columnar phase present but also of the molecular packing and phase transition temperatures. [19] Ordered cylindrical mesopores were observed to impose particular core-shell type of morphologies onto columnar discotics as controlled by curvature effects. [20,21] These exist both for the discotics still located within the pores but also within the isolated nanorods obtained by removing the mesoporous template selectively.…”

Section: Introductionmentioning

confidence: 99%

Lamellar Nanoconfinements Effects in Discotic Liquid Crystalline Block Copolymers

Stillings

Pettau

Wendorff

et al. 2010

Macro Chemistry & Physics

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We have evaluated the effect of slit‐like nanoconfinements imposed on columnar discotic phases within a discotic block copolymer displaying a lamellar microphase. Findings are that the columns are oriented uniformly along the lamellar normal within the plane of thin films, that a rectangular rather than a hexagonal columnar phase is formed within the discotic regions, that the thermodynamic stability of the columnar phase is strongly reduced relative to the low molar mass model compounds and finally, that the isotropic phase can be unusually strongly supercooled with respect to the columnar phase formation. Slit‐like nanoconfinements allow thus to induce novel types of the intrinsic order and columnar orientations.magnified image

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Columnar discotics in confined geometries

Cited by 29 publications

References 25 publications

Morphology of Polymer/Liquid‐Crystal Nanotubes: Influence of Confinement

Morphology of Polymer/Liquid‐Crystal Nanotubes: Influence of Confinement

High-resolution dielectric study reveals pore-size-dependent orientational order of a discotic liquid crystal confined in tubular nanopores

Lamellar Nanoconfinements Effects in Discotic Liquid Crystalline Block Copolymers

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