On the key role of SiO2@POSS hybrid filler in tailoring networking and interfaces in rubber nanocomposites.

The present study provides a comprehensive investigation at the micro and nanoscale of the interface between hybrid SiO 2 @POSS nanofiller, where silica nanoparticles (NPs) and POSS nanocages are intimately interconnected, and Styrene Butadiene Rubber (SBR). SEM and AFM inspection and, more in depth, solid state 1 H NMR revealed a remarkable fraction of rigid rubber close to the SiO 2 @POSS surfaces, which increases with the curing temperature. Instead, a reduced amount of immobilized rubber was detected for SBR/SiO 2 +POSS nanocomposites, obtained by simply mixing SBR, SiO 2 and POSS. The results allowed us to propose a model for the network formation in C-SBR/SiO 2 @POSS. This is based on the progressive activation by dicumylperoxide (DCP) of the methacryl functionalities of POSS nanounits which, being closely connected to SiO 2 NPs in SiO 2 @POSS, promote crosslinking in proximity of the filler surfaces, and lead to the generation of a tight network strongly bonded to the rubber chains. [ABSTRACT FROM AUTHOR]