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Rubber-based nanocomposites prepared by solid-phase mixing with precipitated silica nanoparticles are typically strongly aggregated systems with different levels of spatial organization. The strategy that we developed several years ago to investigate such systems is based on the study of simplified industrial samples with ingredients limited to a strict minimum. On the scale of a micrometric simulation box, tens of thousands of nanoparticles are embedded in the matrix, and their dispersion strongly affects the mechanical properties of the material – and which is reflected in the scattered intensity. A statistical method based on a reverse Monte Carlo solution of this many-parameter problem will be presented, showing that some key features like percolation can be described. [1]Another key feature of rubber nanocomposites refers to the influence of the filler surfaces on the polymer dynamics, and some recent progress – including incoherent neutron spin-echo measurements – will be discussed. [2] Such results may be confronted to dielectric spectroscopy measurements which in some cases are not conclusive due the impossibility to correctly resolve the α-relaxation in presence of strong interfacial polarization processes. An original application of dielectric spectroscopy with a surprising measurement of the adsorption isotherm of coating agents onto silica buried in the polymer matrix will also be discussed. [3]References[1] Musino D, Genix A-C, Chauveau E, Bizien T, Oberdisse J, Nanoscale 2020, 12:3907.[2] Musino D, Oberdisse J, Farago B, Alegria A, Genix A-C, ACS Macro Letters 2020, 9:910.[3] Musino D, Oberdisse J, Sztucki M, Alegria A, Genix A-C, Macromolecules 2020, 53:8083.