Alkoxyamine-functionalized polysilsesquioxane lamellar materials were used as fillers and radical polymerization initiator in the synthesis of nanocomposites. This work is divided into three parts: (i) the synthesis and the characterization of functionnalized-lamellae, (ii) the study of their delamination and (iii) the polymerization leading to the nanocomposites. The presence of covalently bonded siloxane filler reinforced the polystyrene. In addition, the EPR analysis showed that alkoxyamine groups were still present on the nanocomposite and could be homolyzed under thermal condition to enable further potential functionalisations.