Linear self-assembly of nanoparticles within liquid crystal defect arrays

Delphine Coursault (1) , Johan Grand (2) , B. Zappone (3) , Habib Ayeb (1) , G. Levi (2) , Nordin Félidj (2) , Emmanuelle Lacaze (1)

1 INSP - Institut des Nanosciences de Paris
2 ITODYS (UMR_7086) - Interfaces, Traitements, Organisation et Dynamique des Systèmes
3 CNR-INFM - Liquid Crystal Laboratory

We used oily streaks defects of smectic films, oriented by the underlying substrates to create chains of nano-particles of diameter 5nm, gold nano-spheres and quantum dots. Combination of Scanning Electronic Microscopy, fluorescence microscopy and micro-specto-photometry evidenced formation of straight chains of hundreds of micrometers, parallel to the oily streaks, They are constituted of single nano-particles of separation ranging from some micrometers (c'est bien cela?) to 1.5nm when the concentration is increased by ten thousands, in agreement with the most stable sites of trapping located within defects cores, not larger than 5nm. A hierarchy of trapping efficiency is demonstrated in relation with the defect nature. When concentration is further increased, single chains are thickened, but still anisotropic, thanks to the presence of trapping sites around the defccts cores. The hybrid systems with gold nano-particles are consequently optically active and the LSPR can be tuned by light polarization, in a matter controllable by the concentration of GNPs.

Domaines: Matière Molle [cond-mat.soft]

Delphine Coursault, Johan Grand, B. Zappone, Habib Ayeb, G. Levi, et al.. Linear self-assembly of nanoparticles within liquid crystal defect arrays. Advanced Materials, 2012, 24, pp.1461. ⟨10.1002/adma.201103791⟩. ⟨hal-00777951⟩