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Author: Bentz, Dirk ×

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    Research on the synthesis and applicability of surface modified nanoscaled metal oxide particles as curing catalyseres for UV-print-colours and lacquers
    (Saarbrücke : Leibniz-Institut für Neue Materialien, 2009) Becker-Willinger, Carsten; Schmitz-Stöwe, Sabine; Bentz, Dirk
    In the BMBF joint research project - NANOCURE - New Curing Methods for Print-Colours, Glues and Lacquers (prom. ref. : 13N9115) - a new class of nanoscaled photo initiators for radical polymerization processes in the printing industry is to be investigated. A possible mechanism for the reaction of TiO2 with acrylates, which is already described in literature is presented. Different methods of manufacturing TiO2 nanoparticles in the lower nanometric size range and their subsequent processing are described, the method is of special interest as it may lead to a possible integrated production process of UV-printing inks. The TEM analysis shows the homogeneous arrangement of TiO2 nanoparticles in an acrylic matrix, which is a necessary requirement for successful polymerization process. IR-spectroscopy is used to show the effect of TiO2-nanoparticles as UV photocatalytic polymerization initiators.
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    Kinetic investigations on TiO2 nanoparticles as photo initiators for UV-polymerization in acrylic matrices
    (Saarbrücke : Leibniz-Institut für Neue Materialien, 2010) Schmitz-Stöwe, Sabine; Becker-Willinger, Carsten; Bentz, Dirk; Abt, Britta; Veith, Michael
    TiO2 nanoparticles of anatase, useful as photosensitive initiators to induce free radical polymerization in acrylic monomers have been prepared by chemical synthesis. Appropriate surface modification of TiO2 has been achieved in order to compatibilize the particles with the acrylic monomers to obtain an almost homogeneous distribution down to the primary particle size. The surface modification has been additionally fine tuned in such a way, that an efficient transfer of the electrons generated on TiO2 during UV-exposure could be achieved towards the monomer mixture in order to start the polymerization reaction. The formation of the anatase modification could be confirmed by XRD. Particle sizes were determined by UPA, which showed a distribution between 1-10 nm depending on the preparation method used. Transmission electron microscopy carried out with the UV-polymerized coating layers proved the homogeneous distribution of the anatase nanoparticles. Kinetic investigations on the photo-polymerization behavior have been accomplished by photo-DSC and Raman spectroscopy. Curing time was determined in dependence of the materials composition.
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    Morphology controlled preparation of monodisperse TiO2 nanorods and nanoparticles for optical nanocomposites
    (Saarbrücke : Leibniz-Institut für Neue Materialien, 2011) Bentz, Dirk; Becker-Willinger, Carsten; Schmitz-Stöwe, Sabine; Veith, Michael
    Anatase nanoparticles and nanorods were obtained through a modified sol-gel route from titanium(IV) bis(acetylacetonate) diisopropoxide. For particle synthesis a mixture of oleic acid and oleyl amine has been used which offers not only control on particle morphology but also provides organically capped surface modified particles, which can be readily mixed with acrylic monomers yielding completely transparent dispersions. UV- and thermal curing of the monomer / particle mixture lead to clear coatings without any nanoparticle agglomeration.