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C. Lomoschitz, N. Moszner, P. Burtscher, U. Salz, G. Kickelbick:
"Advanced Hybrid Materials In Dentistry";
Talk: Minisymposium: From Molecules to Materials, Saarbrücken, Deutschland; 2009-09-10 - 2009-09-11; in: "From Molecules to Materials", (2009).

Polymer based fillings are successively replacing amalgam as well as glass cement fillings in the area of dental medicine. High biocompatibility and tunable aesthetics were major factors responsible for the high demand of polymer based fillings. Meanwhile, curing times are in an acceptable range and drawbacks such as shrinkage during polymerization and hardness deficiencies havc been overcome by now by embedding of ceramic and/or glass particles into the polymer. However, adhesion between the polymer and the filler or the enamel has to be enhanced, to improve the durability and wear properties of such fillings. Molecular adhesivcs, so called coupling molecules were synthesized in order to create covalent bonds between polymer and an inorganic component (zirconia filier). Therefore, these molecules contain a polymerizable site (methacrylate) and a moiety showing high affmity to metal oxides (phosphoric/phosphonic acid).
Modification of zirconia was carried out under mild conditions in order to conserve the polymerizable moiety. Bonding of the phosphate/phosphonate moiety could be evidenced by means of IR, 31P MAS NMR and XPS. Due to its amphiphilicity, only the phosphoric/phosphonic acid head group interacts with the surface and the alkyl chains and polymerizable moiety respectively are pointing away from the surface. Thermogravimetric measurements proved that the coverage of the particles used were between 50 and 100 % of a theoretically dense monolayer. Furthermore it was shown that coupling molecules containing a long alkyl spacer (C5 or CIO) reveal an orientation on the particle surface. Nitrogen Sorption measurements displayed that the hydrophobic character of the modified surfaces increases with increasing alkyl spacer length, which is accounted for the pending alkyl chains from the particles.

Project Head Guido Kickelbick:
Untersuchung der Wechselwirkungen von Haftkomponenten mit Zirkondioxid- und Edelmetall-Oberflächen sowie Bariumgläsern