Sommaire:

Buiding up hierarchical organizations is still challenging because one have to design self-assembly mechanismes at various length scales and with similar time scales. Two nanoparticle systems are presented. The former system (Fig. 1) is a interplaying between drying processes at nanometric scale (colloidal crystallization) and millimetric scale (Maze Formation within micropatterned surfaces). The second system is the slow crystalisation of polydisperse Ludox®. In both cases, entropy plays an important role with (i) Onsager “Forces” that ease the nematic order between nanorods, and with (ii) mixing entropy in cluster phases.
The former system can be exploited to generate well defined hierarchical organizations with new photophysical properties (superradiance). The Laves phase (Fig. 2) observed in the second system is only the first generation of a clustering process that can generate BCC and AB13 phases of rhombicuboctahedron with more than 500 nanoparticles per unit cell.

Keywords: nanoparticles superlatices, Onsager, mixing entropy, drying, crystallization tolerance.
References
[1] Hamon, et al, ACS. Nano, 2012, 6(5), 4137-4146. Bizien, et al, Small, 2014, 10(18), 3707–3716. Panizza, et al, Phys. Rev. Lett. 2018 121(20), 078002.. Bizien, et al, J. Nanomaterials, 2021, 1790976.
[2] Cabane, et al, Phys. Rev. Lett. 2016, 116(20), 208001. Botet, et al, Faraday Dis., 2016, 186, 229-240. Unpublished Results.

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