Surface initiated polymerization of poly(butyl acrylate) by nitroxide mediated polymerization: First comparative polymerization of a bimolecular and a unimolecular initiator-grafted silica particles

Hybrid silica particles comprising an inorganic core and an organic polymer shell have been synthesized by nitroxide mediated polymerization of butyl acrylate in the presence of a grafted alkoxyamine. The layer of initiator molecules attached to the surface of silica is based on an acyclic beta-phosphonylated nitroxide also referred to SG1. The synthesis and the characterization by NMR of this alkoxyamine structure are briefly described. Moreover, the grafted initiator particles have been studied by XPS, NMR Si-29 CP/MAS, and TGA in order to determine the nature of the anchorage sites and the grafting density.With this stable radical as chain growth moderator tethered to the inorganic core , it is demonstrated that the grafting from polydispersity index(I<1.1). For the first time, a comparitive study with a bimolecular system based on a grafted azoic initiator has been demonstrated and interpreted in terms of variation of the initial [monomer]/[initiator] ratio. [GRAPHIC]