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A novel hybrid nanofiller, SiO 2 @POSS, where the silica nanoparticles (NPs) and the POSS belong to the same functional structure, has been synthesized by grafting different loadings of OctaMethacrylPOSS onto silanized commercial SiO 2 , using a surface reaction mediated by dicumylperoxide (DCP). The peroxide, besides anchoring the nanocages onto the silica surface, ensures the presence of methacryl functionalities in the final structure, which are still available for cross-linking reactions with a polymer host. The hybrid SiO 2 @POSS NPs were used to prepare, by ex situ blending, SBR nanocomposites. The dynamic-mechanical analysis performed on the cured SBR/SiO 2 @POSS composites indicated that the presence of POSS induces a remarkable increase of modulus either at low or at high strain, and a considerable decrease of hysteresis. This has been associated with the peculiar hybrid structure of the SiO 2 @POSS filler, in which silica NP aggregates are partially interconnected and surrounded by a thin shell of POSS nanounits which, thanks to their high number of reactive functionalities, promote the formation of ''sticky regions'' among the silica aggregates and, consequently, a tight filler network wherein rubber is immobilized. This grants a relevant reinforcement and increased hysteretic properties, suggesting SiO 2 @POSS as a promising filler system for decreasing the energy loss under strain and for leading to a potential reduction of filler utilization in rubber composite formulations.

Composites of poly(vinylidene fluoride) (PVDF) and BaTiO3 nanoparticles (average diameter ca. 125 nm) are fabricated by a solvent‐free and industrially scalable technique, that is, melt blending, followed by compression molding. The effect of processing parameters on the spectroscopic, microstructural, thermal, mechanical and dielectric properties are evaluated as a function of composition (loading up to 30 vol%). The presence of nanoparticle inclusions as well as specific compression molding parameters demonstrate both to affect the molecular relaxations of the PVDF matrix, studied by correlating the results of different techniques, and to induce the PVDF crystallization as β phase. Processing parameters also play a key role for optimizing the dielectric properties. An improved dielectric behavior of the composites is obtained in terms of both permittivity, whose value increases up to four times that of neat PVDF, and dielectric losses, lower than 5% between 10 and 3·104 Hz. The obtained performances resulted enhanced compared to analogous composites prepared with the use of solvents.

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