Self-Assembly of Linear and Cyclic Siloxane-Containing Mesogens: Investigation of Layered Structures in Bulk and Thin Films

Authors

  • Paul Heinz ,

    1. Institut für Siliciumchemie, WACKER-Lehrstuhl für Makromolekulare Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching bei München (Germany), Fax: (+49) 89-289-13562
    2. Bayer MaterialScience AG, 51368 Leverkusen (Germany)
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  • Konrad Hindelang,

    1. Institut für Siliciumchemie, WACKER-Lehrstuhl für Makromolekulare Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching bei München (Germany), Fax: (+49) 89-289-13562
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  • Anastasia Golosova,

    1. Fachgebiet Physik Weicher Materie, Physikdepartment, Technische Universität München, James-Franck-Str. 1, 85747 Garching bei München (Germany)
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  • Prof. Christine M. Papadakis,

    1. Fachgebiet Physik Weicher Materie, Physikdepartment, Technische Universität München, James-Franck-Str. 1, 85747 Garching bei München (Germany)
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  • Prof. Bernhard Rieger

    Corresponding author
    1. Institut für Siliciumchemie, WACKER-Lehrstuhl für Makromolekulare Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching bei München (Germany), Fax: (+49) 89-289-13562
    • Institut für Siliciumchemie, WACKER-Lehrstuhl für Makromolekulare Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching bei München (Germany), Fax: (+49) 89-289-13562
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Abstract

Silicon-containing materials which possess the ability to form mesophases are promising systems for applications in the fields of electro-optical devices, nonlinear optics, and information storage media. In this work, the formation of supramolecular assemblies of a series of low molecular weight siloxane-containing mesogens is presented. Besides a novel synthesis route via RuII-catalyzed hydrosilylation of phenyl acetylene derivatives, mesophase characterization by modern analysis techniques is performed. As linker groups, leading to bi- and tetramesogens, linear disiloxane and cyclic tetrasiloxane are utilized. In the resulting class of materials, high thermal stability, induced by the formation of layered smectic-type structures, is predominant. The smectic-type phases were found to be monotropic. Layer distances in the assemblies, as well as the phase transition temperatures, can be controlled by the substitution motif on the mesogens (number and length of alkyl chains). In spin-cast thin films, the layered domains are visualized by atomic force microscopy; furthermore, domain dimensions and electron densities are determined by grazing-incidence small-angle X-ray scattering.

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