No abstract

No abstract

Light elements-based materials are of relevant interest because of their specific physicochemical properties mainly dependent on the involved strong chemical bonds. Among them, diamond and c-BN are still today the most representative materials especially concerning super hardness property. Nevertheless, since the prediction by Liu and Cohen (on the basis of ab initio calculation) of theoretical materials with C 3 N 4 composition exhibiting low compressibility, many efforts have been devoted to the synthesis of carbon nitrides. The first part of this review deals with the brief description of the different predicted C 3 N 4 polymorphs exhibiting either a dense network or a graphitic one. In addition, predicted carbon nitrides with different stoichiometry are also described. The second part presents the analysis of the processing routes described in the literature for the synthesis of carbon nitrides as bulk materials. If many attempts have been devoted to high-pressure processes (direct synthesis, direct conversion from the graphitic form, flux assisted conversion or solvothermal processes), some experiments performed in moderate experimental conditions have also been investigated and appear as really promising. A comparison with the different processes developed for diamond and c-BN is associated. As a conclusion, a discussion about the promising routes related to bulk carbon nitrides synthesis is given.

International audienceA thermoresponsive hybrid system for drug delivery purposes is designed by modifying the surface of silica-coated magnetic lanthanum strontium manganite nanoparticles with block copolymers following a non-covalent approach. Block copolymers containing a short poly(L-lysine) segment and a polyether segment of varying composition are adsorbed through electrostatic interactions between positively charged lysine units and negatively charged SiO− groups at the silica surface, giving rise to mixed polyether brushes with a good control over the chain surface density and thickness of the polymer layer. The thermoresponsiveness of the assemblies is controlled by the ethylene oxide/propylene oxide ratio in the polymer brush and the corresponding LCST of the polyether blocks. Important parameters like the aggregation temperature of the particles can be finely adjusted by modifying this ratio. The polarity of the polymer layer can also be varied to maximize the encapsulation efficiency of a moderately hydrophobic drug like doxorubicin. Drug release experiments are performed by taking advantage of the ac magnetically induced heating properties of the magnetic core to speed up the release of doxorubicin owing to structural changes within the polyether brush