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Directed assembly of nanoparticles monitored by liquid crystal topological defects for advanced optical properties of the composites

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Sprecher: Dr. Emmanuelle Lacaze
Veranstaltung: Montag, den 18. Juni 2018 14:00 - 15:30
Ort: Campus Limpertsberg - Room BSC 2.04

Directed assembly of nanoparticles is a promising alternative for original nanoparticle organisations. New kinds of optical properties are expected when semi-conductive or metallic nanoparticles are concerned.

Using liquid crystal matrices oriented by their interfaces, we create ordered arrays of topological defects [1] that act as traps for nanoparticles, allowing for an anisotropic directed assembly.
For trapped fluorescent nanorods, a fine control of the polarization of the single photons is obtained [2].
Similarly the orientation of gold nanorods leads to the control of their luminescence as well as of their plasmon resonance by light polarization [3].

Dr. Emmanuelle Lacaze will show that, when the nanoparticle concentration is increased, single chains are formed, and can lead to a strong electromagnetic coupling between the particles [3, 4]. "We are not only capable of linearly confining the particles, but also of varying the inter-particle interactions and thus modify their optical properties which are sensitive to the inter-particle distance [4]. The chains being oriented by the defects, the electromagnetic coupling becomes controlled by light polarization [3-5]. We now also show how to use the easy activation of the liquid crystal matrix to modify on purpose these nanoparticle organizations."

[1] D. Coursault et al., Soft Matter 12 (2016) 629.
[2] L. Pelliser et al, Adv. Funct. Mat. 25 (2015) 1719.
[3] B. Rozic et al., ACSNano (2017).
[4] D. Coursault et al., Adv. Mat. 24 (2012) 1461.
[5] D. Coursault et al., ACSNano 9 (2015) 11678.

Daten: 2018_06_18_Emmanuelle Lacaze_PS.pdf 423,77 kB