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Résumé:

Graphene oxide dispersions are easily obtained in water. Due to the high aspect ratio of the flakes, liquid crystalsthen forms a nematic phase at moderate concentrations [1,2], which allows to design various composites withnanoparticles. Preparing organized materials and thin films from these dispersions however requires a good controlof the liquid crystal ordering during the deposition and the drying of the films.Here we have focused on mechanical instabilities that are frequently observed in thin graphene liquid crystallayers, when they are submitted to weak constraints. We have shown how to create and stabilize large-sizedperiodic textures (millimeter scale, see fig.1). The patterns have been characterized under optical and electronicmicroscopies. They result from the peculiar elastic and rheological properties of the graphene oxide liquid crystals.Our results also clarify why long-standing hypotheses on the presence of exotic phases [1] at large concentrationsare present in the literature.