A series of organic‐inorganic hybrid particles were synthesized by a self‐assembled layer of different initiators, immobilized on silica particles and used for controlled radical polymerization. We use three different initiator systems for atom‐transfer radical polymerization (ATRP), unimolecular nitroxide mediated polymerization (NMP), and bimolecular NMP, for the development of the hybrid inorganic/organic particles. After preliminary qualitative characterization by X‐ray spectroscopy (XPS) and Fourier‐transformed infrared (FT‐IR) measurements, the hybrid nanoparticles were studied by thermogravimetric analysis (TGA) to determine and discuss the initiator graft density in terms of steric hindrance.The coupling agents employed for the various approaches used here: a) NMP1‐bimolecular system, b) NMP2‐unimolecular system, and c) ATRP.magnified imageThe coupling agents employed for the various approaches used here: a) NMP1‐bimolecular system, b) NMP2‐unimolecular system, and c) ATRP.

Summary: Amphiphilic diblock copolymers consisting of a hydrophilic block, poly(acrylic acid), and a hydrophobic block, polystyrene, were synthesized by direct nitroxide‐mediated polymerization using the PS block as a macro‐initiator for the first time. Several techniques were used to characterize the amphiphilic block copolymers (size exclusion chromatography, NMR spectroscopy). The proposed method can lead to samples with a broad range of composition and molar mass. Preliminary studies of their self‐assembly in aqueous medium using fluorescence spectroscopy and small‐angle neutron scattering are presented.Schematic of the formation of the PS‐b‐PAA block copolymers and their micellization in aqueous media.imageSchematic of the formation of the PS‐b‐PAA block copolymers and their micellization in aqueous media.

No abstract

Summary: 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 β‐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 29Si 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 polymerization exhibits a control character with a very low polydispersity index (I < 1.1). For the first time, a comparative study with a bimolecular system based on a grafted azoic initiator in presence of SG1 is also described. A different kinetic behavior has been demonstrated and interpreted in terms of variation of the initial [monomer]/[initiator] ratio.

Block copolymers based on poly(vinylidene fluoride), PVDF, and a series of poly(aromatic sulfonate) sequences were synthesized from controlled radical polymerizations (CRPs). According to the aromatic monomers, appropriate techniques of CRP were chosen: either iodine transfer polymerization (ITP) or atom transfer radical polymerization (ATRP) from PVDF‐I macromolecular chain transfer agents (CTAs) or PVDF‐CCl3 macroinitiator, respectively. These precursors were produced either by ITP of VDF with C6F13I or by radical telomerization of VDF with chloroform, respectively. Poly(vinylidene fluoride)‐b‐poly(sodium styrene sulfonate), PVDF‐b‐PSSS, block copolymers were produced from both techniques via a direct polymerization of sodium styrene sulfonate (SSS) monomer or an indirect way with the use of styrene sulfonate ethyl ester (SSE) as a protected monomer. Although the reaction led to block copolymers, the kinetics of ITP of SSS showed that PVDF‐I macromolecular CTAs were not totally efficient because a limitation of the CTA consumption (56%) was observed. This was probably explained by both the low activity of the CTA (that contained inefficient PVDF‐CF2CH2I) and a fast propagation rate of the monomer. That behavior was also noted in the ITP of SSE. On the other hand, ATRP of SSS initiated by PVDF‐CCl3 was more controlled up to 50% of conversion leading to PVDF‐b‐PSSS block copolymer with an average number molar mass of 6000 g·mol−1. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Hybrid silica particles comprised of an inorganic core and an organic polymer shell can be synthesized by surface‐initiated nitroxide‐mediated polymerization (SINMP) in the presence of a grafted alkoxyamine as initiator. The layer of initiator molecules attached or adsorbed to the particles surface is based on a nitroxide group. The synthesis and characterization of these alkoxyamine structures are briefly described. The grafted initiator particles are studied in order to determine the nature of the anchorage sites and the grafting density. With a stable radical or nitroxide as chain‐growth moderator tethered to the inorganic core, it was demonstrated that the grafting from or to SINMP exhibits a control character with a very low polydispersity and good agreement between theoretical/experimental molecular weights. A comparative review of different alkoxyamines with a bimolecular system based on a grafted azoic initiator in the presence of an acyclic β‐phosphonylated nitroxide called SG1 is also described. Moreover, original methods for the synthesis of alkoxyamine grafted surface by in situ trapping of carbon radicals and some new developments for colored pigments will be reported. These topics could be one of the directions of the field in the next years. Copyright © 2006 Society of Chemical Industry