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B. Feichtenschlager, G. Kickelbick, T. Koch, C. Lomoschitz, S. Pabisch, H. Peterlik, M Sajjad:
"Ordering Phenomena Of Organic Moieties On Nanoparticle Surfaces And Their Influence On The Dispersibility In Organic Media";
Poster: 13. Österreichische Chemietage, Wien; 2009-08-24 - 2009-08-27; in: "13. Österreichische Chemietage", (2009), ISBN: 978-3-900554-66-8; 1 pages.

Capping agents increase the compatibility at the interface in polymer nanocomposite materials resulting in a better dispersibility of inorganic nanobuilding blocks in an organic matrix. In addition to the surface-adaption the capping agent may also contain functional groups allowing a covalent linkage to a polymer system during an in situ polymerization. Many reports in literature describe the use of long alkyl chains for this purpose. However, such long alkyl-chains tend to form very well ordered structures, such as self-assembled monolayers, on the surface of the nanobuilding blocks. In some cases this can lead to a decrease in dispersibility due to interparticle aggregation phenomena. Here we present two routes which can solve this problem: On the one hand the mixing of two different coupling agents can break the ordering phenomena on the surface of the particles, on the other hand flexible chains can avoid ordering phenomena. Zirconia nanoparticles (22 nm diameter) with a very uniform sizedistribution were used as model systems to prove these hypotheses. As surface modifying agents phosphonic acids were used with various organic functionalities. Ordering phenomena of alkyl chains at the particle surface were analyzed via infrared spectroscopy studies (IR). The dispersibility of the modified particles in organic media was investigated by dynamic light scattering (DLS) and small angle X-ray scattering (SAXS) experiments. The particles were used as building blocks for the preparation of nanocomposites with poly(methyl methacrylate), polystyrene or epoxy resin formulations as polymer matrix.

Project Head Guido Kickelbick:
Chemisch massgeschneiderte Grenzflächen in Nanokompositen