Characterization of octamethylsilsesquioxane (CH3)8Si8O12 fillers in polypropene matrix

POSS-based (polyhedral oligomeric silsesquioxane) materials, including biomaterials, dielectric materials, organic light-emitting diodes, lithography resists, catalysts, membrane fuel cells, and battery membranes have recently been introduced [1]. In nanocomposites, advantageous changes of the materials properties, are usually connected to the filler particle's surface properties and interfacial interactions because of the large surface-area-to-volume ratio of the filling material. Yet, properties such as structure and orientation of the filler in the polymer matrix may play a crucial role in understanding the whole subject. The octamethyl-POSS (om-POSS) [(CH3)8Si8O12] filler material has been shown to have ability to substantially increase the breakdown strength of polypropylene (PP) [2]. The results of the relative permittivity, loss factor and volume resistivity measurements indicate that om-POSS additives could improve the dielectric properties of PP. In this work multi-level characterization of om-POSS fillers in composite material is performed using X-ray tomography, powder diffraction, transmission electron microscopy and micro-Raman facilities at the University of Jyväskylä. The detailed analysis of micro-Raman measurements is done at Tampere University of Technology using electron-scale ab initio density functional theory (DFT) based methods. All polymer nanocomposite samples have been developed at the Technical Research Centre of Finland (VTT). The research has been funded by the Tekes consortium project NANOCOM.