Hyperverzweigte Polyetherpolyole mit flüssigkristallinen Eigenschaften

Sunder, Alexander; Quincy, Marie-France; Mülhaupt, Rolf; Frey, Holger

doi:10.1002/(sici)1521-3757(19991004)111:19<3107::aid-ange3107>3.0.co;2-c

Cited by 8 publications

(2 citation statements)

References 25 publications

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“…Investigations on multipodal and dendritic liquid crystal systems have so far mainly been focused on the materials that perform layered, columnar, and cubic-phase structures . However, the systems that exhibit nematic phase behavior have also recently attracted considerable attention.…”

Section: Introductionmentioning

confidence: 99%

Orientational Order and Dynamics of Nematic Multipodes Based on Carbosilazane Cores Using Optical and Dielectric Spectroscopy

Tajber¹,

Kocot²,

Vij³

et al. 2002

Macromolecules

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The birefringence, refractive indices, and dielectric measurements have been carried out for the double- and triple-branched multipodes based on the carbosilazane cores. The orientational order parameters have been obtained using both the optical and the dielectric measurements. The dielectric response is identified to arise from the dipoles of the carboxyl and the alkoxy groups in the ortho position of the benzene ring. Results are analyzed in the framework of the mean-field theory. At least three molecular modes are resolved in the dielectric relaxation spectra in the nematic phase. The lower frequency process is retarded, and the other two processes are accelerated significantly with respect to the relaxation rate in the isotropic phase. The acceleration effect is even much stronger than the retardation effect. The acceleration factors are also found to be much higher than those for the low molar mass nematic liquid crystals. These results show that the anisotropy of the macromolecule plays a significant role in determining the nematic potential which governs the relaxation dynamics. The results on the relaxation dynamics show that the mesogens are decoupled from the core of the macromolecules.

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Section: Introductionmentioning

confidence: 99%

Orientational Order and Dynamics of Nematic Multipodes Based on Carbosilazane Cores Using Optical and Dielectric Spectroscopy

Tajber¹,

Kocot²,

Vij³

et al. 2002

Macromolecules

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“…[1][2][3] Only dendritic molecules with peculiar architectures were shown to be capable of forming self-assembled one-dimensional supramolecular structures such as rods, fibers, ribbons, and helices, which are of special interest for nanotechnology. [12][13][14][15] It is widely accepted that a precise matching of directional interactions and steric constraints is required to facilitate long-range one-dimensional supramolecular assembly. [4][5][6][7][8][9][10] A proper combination of steric constraints, stacking interactions, and hydrogen bonding is postulated to be critical for precise assembly of these molecules.…”

mentioning

confidence: 99%

Nanofibers from Functionalized Dendritic Molecules

et al. 2004

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Ein Teil des Inhalts dieser Zuschrift überlappt erheblich mit einer ausführlichen Veröffentlichung derselben Gruppe, die unter dem Titel "Assembling of Amphiphilic Highly Branched Molecules in Supramolecular Nanofibers" in J. Am. Chem. Soc. 2004, 126, 9675-9684 erschienen ist. Obwohl beide Arbeiten zur gleichen Zeit eingereicht wurden, stellten die Autoren den Herausgebern der Angewandten Chemie keine Kopie der ausführlichen Veröffentlichung zur Verfügung. Dies führte zum gleichzeitigen Erscheinen derselben Information in zwei Veröffentlichungen. Die Autoren entschul-digen sich für diesen Fehler.

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Nematic Dendrimers Based on Carbosilazane Cores

et al. 2001

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Research on dendritic liquid crystal systems has focused mainly on the investigation of materials that exhibit layered, columnar, cubic-phase structures. [1, 2] The emphasis has been associated with the chemical structure of these systems, in which a dendritic core and a periphery consisting of functional groups of different chemical composition, which are responsible for self-assembly processes, leads to nanoscopic phase segregation between core and periphery. [3,4] Thus, well-defined dendritic systems that exhibit nematic phase behavior and that are characterized only by orienta-tional ordering and contain functional groups promoting nanophase separation have attracted considerable interest. The opposing forces of the nematic director field, which are attributed to the peripheral mesogens, and the tendency of the dendritic cores to undergo phase separation should lead to a new class of compounds with interesting properties in the liquid-crystalline (LC) state. [5] This structural concept should allow the decoupling of the transition behavior and the ordering of the LC phase from the size of the molecules, which is a long-standing aim of LC polymer research. The materials should additionally be characterized by comparatively low viscosities.The use of carbosilazane cores 1 ± 5, which display an overall threefold symmetry and possess a planar central core, allows the synthesis of microphase-separated systems. [6] The

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Hyperverzweigte Polyetherpolyole mit flüssigkristallinen Eigenschaften

Cited by 8 publications

References 25 publications

Orientational Order and Dynamics of Nematic Multipodes Based on Carbosilazane Cores Using Optical and Dielectric Spectroscopy

Orientational Order and Dynamics of Nematic Multipodes Based on Carbosilazane Cores Using Optical and Dielectric Spectroscopy

Nanofibers from Functionalized Dendritic Molecules

Nematic Dendrimers Based on Carbosilazane Cores

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