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ZnO nanoparticles surface functionalized with α-oxo-carboxylic acids have been used as photo-initiators for the curing of UV off-set printing inks. Other than commercial molecular photo-initiators ZnO nanoparticles do not migrate in the cured resins, they do not leach out and therefore, even if in contact with food, there is no danger of contamination. ESR and in-situ Raman-spectroscopy have been applied to analyze the kinetics of this free radical bulk photo-polymerization process. Upon UV irradiation the Photo-Kolbe-reaction (decarboxylation of carbonic acids by the photo generated electron hole) takes place as could be confirmed by ESR and GC-MS measurements.

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Silica-or meso-silica-or silica-meso-silicacoated copper oxide microspheres were prepared based on base hydrolysis of tetraethyl orthosilicate in the presence of CuO and CTAB. Functionalization with amine or thiol organofunctional groups was conducted onto the surface of silica-meso-silica-coated copper oxide microspheres (Scheme 1). The silica-coated CuO composites and their amine-or thiol-functionalized materials have been characterized by TEM, XRD, TGA, FTIR and UV/Vis. TEM analysis showed that the CuO nanoparticles were encapsulated and dispersed into the silica or meso-silica microspheres. XRD analysis indicated that the size of CuO nanoparticles has decreased after coating with silica precursors. TGA and FTIR results indicated that the mesosilica-coated copper oxide materials have been successfully grafted by amine and thiol organofunctional groups. Graphical Abstract

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Silica (SiO 2) and mesoporous silica (mSiO 2) coated magnesium oxide composites were prepared based on hydrolysis and co-condensation of tetraethylorthosilicate (TEOS) in presence of magnesium oxide nanoparticles (MgO-NPs) and cetyltrimethylammonium bromide (CTAB). Functionalization with thiolorganofunctional silane precursor was conducted onto the surface of mesosilica (Scheme 1). Silica coated MgO composites and its thiol functionalized material have been characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope, Fourier transform spectroscopy (FTIR), ultra violet-visible spectra and thermal analysis (TGA). TEM analysis showed that the MgO nanoparticles were encapsulated into the SiO 2 or mSiO 2 precursors. XRD analysis reveals that magnesium oxide are exist into both forms, cubic MgO-structure and hexagonal Mg(OH) 2-structure, which is converted into cubic structure upon silica coating. The mean crystallite size of MgO-NPs remains almost unchanged after coating with silica precursors. TGA and FTIR results indicated that the coated mesosilica layer around magnesium oxide nanoparticles has been successfully grafted by thiolorganofunctional silane groups.