Nanocomposites and nanomaterials

Helical assemblies of nanoparticles with reconfigurable structures
Pawlak M.1, Bagiński M.1, Lewandowski W.1
1 Faculty of Chemistry, University of Warsaw, ul. Pasteura 1, 02-093 Warsaw 
E-mail: mr.pawlak@student.uw.edu.pl

Plasmonic chirality can be achieved by combining achiral nanoparticles with chiral templates. One of the yet not used is a B4 phase, which is semi-crystalline phase, where due to twist of smectic layers, helical nanofilaments are formed. B4 phase is chiral, since it is not possible to superimpose left- and right-hand twisted helix.
We are reporting hybrid assemblies of spherical gold nanoparticles with liquid-crystalline organic shell in mixture with number of bent-core liquid crystals able to formation of helical nanofilaments. Obtained structures were observed on transmission electron microscopy (TEM). Small-angles X-ray diffraction (SAXS), wide-angles X-ray diffraction (WAXS) and differential scanning calorimetry (DSC) measurements were performed. 
Results confirmed existence of B4 phase in samples and ability to helical nanofilaments formation depends on length of molecular core. Moreover chemical compatibility between nanoparticles shell and helical matrix is crucial for assembly of nanoparticles on helices surface.

Fig. 1. TEM image of helical gold nanoparticles assembly

The research is conducted under Reinforce project carried out within the First Team programme of the Foundation for Polish Science co-financed by the European Union under the European Regional Development Fund.