Résumé
To date, aqueous stable graphene flakes solutionscan be obtained by simple REDOX reactions.1–5 Most of the current applications regardinggraphene require ordered nanostructuredcomposites materials. Liquid crystal phases orderingrepresent an opportunity to arrange theminto macroscopic assemblies with long-rangeordering. 1,2 Preparing organized materials andthin films from these dispersions then requires agood control of the liquid crystal ordering duringthe deposition and the drying of the films. As amatter of fact, it turns out that graphene flakeseasily align at high shear.3,4 On the other hand,Graphene Flakes Liquid Crystals (GFLC) exhibita very interesting behaviour at low shear or undersmall displacements, thin films often showspeculiar patterns (such as the periodic texturesshown in Fig.72-72). We have shown how tocreate and stabilize large-sized periodic texturesin GFLC. The patterns have been characterizedunder optical and electronic microscopies. Theirstability can be explained by the competition betweenthe anchoring field of the substrate andthe presence of a yield stress resulting fromthe peculiar elastic and rheological properties ofthe GFLC. Our findings also clarify why longstandinghypotheses on the presence of exoticphases1 at large concentrations are present inthe literature.
References[1] Zakri, C.; Blanc, C.; Grelet, E.; Zamora-Ledezma, C.; Puech, N.; Anglaret, E.; Poulin, P. Philosophical Transactions of theRoyal Society A: Mathematical, Physical and Engineering Sciences 2013, 371, 20120499..
[2] Zamora-Ledezma, C.; Puech, N.; Zakri, C.; Grelet, E.; Moulton, S. E.; Wallace, G. G.; Gambhir, S.; Blanc, C.; Anglaret, E.;Poulin, P. The journal of physical chemistry letters 2012, 3, 2425–2430..
[3] Poulin, P.; Jalili, R.; Neri, W.; Nallet, F.; Divoux, T.; Colin, A.; Aboutalebi, S. H.; Wallace, G.; Zakri, C. Proceedings of theNational Academy of Sciences 2016, 113, 11088–11093..
[4] Zamora-Ledezma, C.; Jeridi, H.; Anglaret, E.; Blanc, C. Orientations and periodic textures in graphene liquid crystals. 27thInternational Liquid Crystal Conference (ILCC2018). 2018..
[5] Xu, Z.; Gao, C. Nature communications 2011, 2, 571.