- 03 Juin 2022
- 11h00 - 0h00
Clémence Chinaux-Chaix – Binary supercrystal assembly controlled by ligand and bad solvent effects
Laboratoire de Physique et Chimie des Nano-objets (LPCNO), Toulouse
Organization of nano-objects of different nature can lead to superstructures1 that combine their functional properties2 (magnetic, semiconducting, luminescent, catalytic, etc.). A broad range of structuration may be envisioned, depending on the processes of self-assembly of the building blocks: periodic superlattices, quasiperiodic arrangements or aperiodic assemblies. In this work, we focused on the formation of periodic assemblies of spherical nanoparticles, and we studied some ligand effects on
the formation of superlattices. Work on single component systems, as well as on binary assemblies, has been investigated.
Among the parameters that affect nanoparticle self-assembly, the stabilizing coordination sphere of ligands plays a main role. Several works have been reported revealing the importance of the size ratio between the ligand length and the radius of the nanocrystal core3. In a first part, we will explain how the presence of an excess of ligand in the system can also have a strong influence of the assembly. Working with small gold nanoparticles in presence of oleylamine (OAm), we have observed that an increasing excess of ligand leads to a structural change of the superlattice structure from FCC to BCC (Fig. 1). Interestingly, a novel primitive hexagonal structure has been observed for some nanoparticle sizes. In a second part, ligand size effects will be detailed in the frame of binary assembly of gold and ruthenium nanoparticles. On the other hand, the presence of bad solvent appears to be a parameter that affect the self-assembly of nanoparticles4. In a third part, we will present how the presence of a bad solvent can selectively precipitate nanoparticles in solution.
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