Kinetic investigations on TiO2 nanoparticles as photo initiators for UV-polymerization in acrylic matrices

Abstract

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.