[Zurück]

M.-A. Néouze:
"Building and Tailoring Ionic Nanoparticle Networks";
Vortrag: MRS Spring Meeting 2012, San Francisco (eingeladen); 09.04.2012 - 13.04.2012; in: "MRS Spring Meeting 2012 - Program & Exhibit Guide", (2012), S. AAA2.3.

Recently ionic nanoparticle networks (INN) were reported in the frame of the remarkable development of new inorganic-organic hybrid materials based on nanoparticle assembly. The original method we developed to synthesize 3-D networks is based on the functionalization of metal oxide nanoparticles with ionic linkers, the bridging ligands containing imidazolium units. Recent publications pointed out the powerful synergy of ionic species with nanoparticles. Such synergy makes those new inorganic-organic hybrid materials promising candidates for many applications such as catalysis or electrolytes.
The length and rigidity of the imidazolium bridging units was varied. The short-range order of the network was investigated via small-angle X-ray scattering. This short-range order was interpreted as originating from self-organization of the aromatic rings of the ligands bridging the nanoparticles by means of π-stacking. This hypothesis was validated by luminescence investigations on the hybrid materials. Anion metathesis reactions were performed on ionic silica networks based on imidazolium chloride bridging units. The investigated salts were NaBF4, KPF6 and LiN(SO2CF3)2. X-ray diffraction experiments and Nuclear Magnetic Resonance analysis allowed following the anion metathesis. Small-angle X-ray scattering experiments confirmed that the anion metathesis only very slightly affected the short-range order of the network and did not influence the luminescence properties. The yield of the metathesis reaction was evaluated by energy dispersive X-ray spectroscopy. The anion metathesis reaction provides a tailoring tool for the hybrid material hydrophilicity. Additionally the methodology was extended towards the formation of hybrid material thin films using a layer-by-layer deposition method for the formation of imidazolium-based assemblies of photocatalytic titania nanoparticles. This provides a new route for the controlled processing of this promising class of materials.