Nitroxide Mediated Polymerization of Styrene from Ladder‐Like Polysilsesquioxane: Synthesis and Characterization of Inorganic–Organic Hybrid Materials

ABSTRACT Due to their shape, thermal and mechanical stability, and high content of functional groups, ladder polysilsesquioxanes (LPSQs) are attractive structures for the design of hybrid materials. In this article, we describe the syntheses of two macroalkoxyamines‐grafted LPSQs that differ in the nature of radicals released upon thermal initiation, which can be a nitroxide or a benzyl radical. Styrene nitroxide‐mediated polymerization using these initiators is described. The impact of alkoxyamine structures on the polymerization process and on the properties of the hybrid materials formed is discussed. The kinetic studies reveal that, regardless of the specific LPSQ‐macroalkoxyamine combination used, the styrene polymerization is not fully controlled, leading to high dispersity in the final hybrid materials. Nevertheless, the LPSQ‐macroalkoxyamine which releases benzyl radical shows a better polymerization control in terms of molecular weight than the one releasing nitroxide radical. The resulting hybrid polystyrene grafted LPSQs exhibit enhanced thermal and viscoelastic properties in the form of increased glass transition temperature, storage, and loss moduli compared to their organic analogues and the simple PS/LPSQ blend, even at low silica loadings.