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Self‐Assembly of Linear and Cyclic Siloxane‐Containing Mesogens: Investigation of Layered Structures in Bulk and Thin Films
Author(s) -
Heinz Paul,
Hindelang Konrad,
Golosova Anastasia,
Papadakis Christine M.,
Rieger Bernhard
Publication year - 2011
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201100301
Subject(s) - mesophase , hydrosilylation , siloxane , materials science , disiloxane , lamellar structure , thin film , crystallography , thermal stability , supramolecular chemistry , phase (matter) , liquid crystal , polymer chemistry , chemical engineering , nanotechnology , organic chemistry , chemistry , composite material , polymer , optoelectronics , crystal structure , catalysis , engineering
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 Ru II ‐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.