Synthesis and Characterization of SCLC-Homopolymers and Blockcopolymers

Abstract

We summarize the syntheses and ring-opening metathesis polymerisation (ROMP) of bis[(4-cyanobiphenyl-4-yl)oxy-n-alkyl]norborn-5-ene-2,3-dicarboxylates with alkyl chain length n = 3, 5, 6 and 9 using the molybdenum-carben initiator Mo(CH-tBu)(NAr)(OCR₃)₂. The influence of the stereochemistry of the double bond depending on the various initiators with R = CF₃ or CH₃ or a Ru-system of the Grubbs type are investigated by X-ray diffraction, neutron scattering and thermoanalytical methods. Besides the homopolymers, well-defined block copolymers with cyclooctene as comonomer were also synthesized via ROMP and we report the morphology studies on side chain liquid crystalline block copolymers. All copolymers show thermotropic liquid crystalline phases, depending on the spacer-length they show either nematic (n = 3, 5) or smectic (n = 9) textures. The morphology of a smectic block copolymer is characterized by different methods, like atomic force microscopy (AFM), small angle X-ray spectroscopy (SAXS) and transmission electron microscopy (TEM).