Abstract
This work deals with the ecodesign of ordered mesoporous silica (SMO) functionalized by polymers, which combine the advantages of mesoporous materials and those of polymers. The materials were structured by polyion complex (PIC) micelles, formed by electrostatic complexation between a polyamine (oligochitosan) and a double-hydrophilic block copolymer (DHBC). The copolymer has a functional polyacid block and a neutral PEO block that remained anchored in silica walls during the sol-gel process. The functional groups were revealed in the mesopores after the release of polyamines induced by PIC micelle dissociation upon a pH change. During this thesis, we expanded the synthesis route to a variety of mesostructures, morphologies and acid functions (poly(acrylic acid), poly(sulfonic acid)). First, the mesostructure was controlled by modifying the pH, the length of the oligochitosan and the conformation of the DHBC (linear PEO or brush-like PAPEO), resulting in SMO with lamellar, 2D hexagonal, and spherical cubic structures. The results were interpreted in terms of PIC assemblies morphology changes and allowed establishing a phase diagram. Then, a method was developed to control particle growth and ensure their stabilization by replacing part of the structuring DHBC by a stabilizing polyacrylamide-based DHBC (PAM-b-PAA). Nanoparticles were obtained with adjustable sizes between 200 nm and 1000 nm, well-defined morphology and ordered structures. The dissociation of PIC micelles in materials was then optimized to synthesize materials with a high density of acid functions in their mesopores (2.7 per nm3). Various materials with controlled size, structure and acidity were thus obtained. They were evaluated as adsorbents, catalysts and proton conductors. Of particular interest are the strong polyacid functionalized materials, exhibiting a very high proton conductivity (> 0,02 S.cm-1) stable over days.