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B. Feichtenschlager, G. Kickelbick:
"Poly(dimethylsiloxane) chain modified metal oxide nanoparticles as new building blocks for inorganic-organic-nanocomposites";
Poster: Frontiers in Silicon Chemistry 2011, Munich, Germany; 14.04.2011 - 15.04.2011; in: "Frontiers in Silicon Chemistry 2011", (2011), S. A45.

A common approach in the interfacial-compatibility-enhancement, to yield a homogeneous dispersion in inorganic-organic nanocomposites, is the use of long alkyl chains as endcappings of the inorganic building blocks. We investigated on use of poly(dimethylsiloxane) (PDMS) chains as alternative for 3 major reasons: (i) Long alkyl chains can form thermodynamically very stable self assembled monolayers at the nanoparticle surface which can result in the formation of interparticle bilayers and thus very stable aggregates which is undesired in terms of homogeneous nanomaterials. Flexible PDMS-chains should avoid that. (ii) A soft interface, provided by PDMS between inorganic and organic part in a nanomaterial should offer interesting new mechanical properties. (iii) These type of surface functionalized nanofillers should be ideal systems for the incorporation in silicone-resin.
In our study we used 22 nm diameter ZrO₂ and 9 nm and 60 nm diameter SiO₂ nanoparticles. For the attachment of the PDMS chains to ZrO₂, the phosphonic acid anchor group was used and trialkoxysilane groups were used for the modification of the SiO₂ surfaces. We developed and evaluated two different principles for the covalent attachment of PDMS chains to the metal oxide nanoparticle surfaces: A grafting-onto approach where a polymeric capping agent is directly attached to a metal oxide nanoparticle surface. Also a grafting-from approach where initiator-molecules or initiator precursors are attached to the nanoparticle surface and a (living) anionic ring opening polymerization is started from the surface to give PDMS-chains.

Projektleitung Guido Kickelbick:
Chemisch massgeschneiderte Grenzflächen in Nanokompositen