Print Email Facebook Twitter Molecular ordering in the high-temperature nematic phase of an all-aromatic liquid crystal Title Molecular ordering in the high-temperature nematic phase of an all-aromatic liquid crystal Author Vita, F. Hegde, M. Portale, G. Bras, W. Ferrero, C. Samulski, E.T. Francescangeli, O. Dingemans, T. Faculty Aerospace Engineering Department Aerospace Structures & Materials Date 2016-01-19 Abstract We report the structural characterization of the nematic phase of 2,6-biphenyl naphthalene (PPNPP). This lath-like all-aromatic mesogen provides a valuable benchmark for classical theories of nematic order. PPNPP exhibits a very high temperature nematic phase (417–489 °C) above an enantiotropic smectic A phase. X-ray diffraction reveals a surprisingly strong tendency towards molecular layering in the nematic phase, indicative of “normal cybotaxis” (i.e. SmA-like stratification within clusters of mesogens). Although stronger at low temperatures, the layering is evident well above the smectic A-nematic transition. The nematic order parameter is evaluated as a function of temperature from the broadening of the wide-angle diffuse diffraction feature. Measured values of the orientational order parameter are slightly larger than those predicted by the Maier–Saupe theory over the entire nematic range except for a narrow region just below the clearing point where they significantly drop below the theoretical prediction. Subject Gold for GoldOpen Access To reference this document use: http://resolver.tudelft.nl/uuid:b787debd-6a83-4314-8cd6-a7d14fbc653b DOI https://doi.org/10.1039/C5SM02738A Publisher RSC Publishing ISSN 1744-6848 Source Soft Matter, 2016, Advance Article Part of collection Institutional Repository Document type journal article Rights (c) 2016 RSC Files PDF c5sm02738a.pdf 2.16 MB Close viewer /islandora/object/uuid:b787debd-6a83-4314-8cd6-a7d14fbc653b/datastream/OBJ/view