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Issue 1, 2017
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Body-centred cubic packing of spheres – the ultimate thermotropic assembly mode for highly divergent dendrons

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Abstract

We have synthesized sodium tris(alkoxy)benzoates in which one of the three alkyl chains branches further into three C18H37 chains. These AB5 hyperbranched minidendrons melt directly into a body-centred cubic (BCC) mesophase formed by spherical “micelles”. In contrast, their non-branched counterparts display various mesophases before they turn into BCC upon heating. This agrees with the predictions from a numerical geometric model that relates the shape of the molecular wedge to the type of mesophase they adopt. The spheres were found to shrink in volume upon heating and expand upon cooling, as molecules, in some cases nearly half of them, are ejected and reintegrated in the spheres. The ejection of dendrons is caused by their lateral thermal expansion. The BCC appears to be the ultimate mesophase for the extremely divergent wedges such as the hyperbranched minidendrons. In dendrons with chains of unequal length, the sphere size is fixed by the shorter chains, the longer ones back-folding or interdigitating to effectively widen the wedge. This new understanding of their assembly will help in designing new dendrons, e.g. for better encapsulation of guest molecules.

Graphical abstract: Body-centred cubic packing of spheres – the ultimate thermotropic assembly mode for highly divergent dendrons

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Publication details

The article was received on 17 Aug 2016, accepted on 27 Sep 2016 and first published on 27 Sep 2016


Article type: Communication
DOI: 10.1039/C6NH00155F
Citation: Nanoscale Horiz., 2017,2, 43-49
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    Body-centred cubic packing of spheres – the ultimate thermotropic assembly mode for highly divergent dendrons

    X. Yao, L. Cseh, X. Zeng, M. Xue, Y. Liu and G. Ungar, Nanoscale Horiz., 2017, 2, 43
    DOI: 10.1039/C6NH00155F

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