Tailoring the Dielectric and Mechanical Properties of Polybutadiene Nanocomposites by Using Designed Ladder-like Polysilsesquioxanes

In this study, the preparation of polybutadiene/polysilsesquioxane nanocomposites (NCs) having tunable thermomechanical and dielectric properties is reported. This was achieved by using different amounts of a filler consisting of a silsesquioxane with a defined ladder-like molecular structure (LPMASQ) bearing reactive methacrylate functionalities. In detail, solid-state nuclear magnetic resonance (NMR) investigation revealed that an increasing amount of filler leads to a progressive homopolymerization of LPMASQ units resulting in the generation of domains in the composites, which induce a kind of polymer chain confinement in proximity of the hybrid interface. The evolution of the molecular organization of the inorganic nanobuilding blocks as a function of their concentration has been highlighted also by small-angle X-ray scattering (SAXS) experiments. The gradual assembly of LPMASQ units gives rise to peculiar dielectric properties along with enhanced thermal and mechanical stability of the final NCs, thus supplying suitable materials for applications in high performance dielectrics. Furthermore, these outcomes support the idea that a careful control of the molecular architecture and organization of the silsesquioxanes in a polymer matrix allows to simultaneously modulate two or more distinct functional features of polymer NCs.