Introduction Nanostructured materials have attracted substantial interest in many fields of science because of their potential application [ 1 ]. Among them the ordered mesoporous silicas, such as MCM-41 or SBA-15, exhibiting
sustainability. Recent study within the sol–gel area has enabled phosphorus-silicon synergisms to be studied as alternatives [ 11 – 20 ]. Usually the success in such nanocomposite systems refers to the formation of silica nanoparticles (eventually doped with
Surface characterization of various silicas
A tentative correlation between the energies of adsorption sites and the different biological activities
In order to correlate the biological activity of silica to its surface properties, the analysis of surface sites on three kinds of silicas of different origins and textures has been performed by adsorption calorimetry.
functionalization, and of inorganic components such as excellent mechanical and thermal stability. Moreover, mesoporous carbon/silica nanocomposites can also facilitate thermal, chemical, conductive and mechanical properties. Confinement effects inside the mesopores
The interaction between TEOS and some polyols
Thermal analysis and FTIR
Abstract
Hybrid organic-inorganic materials, silica – polyols (ethylene-glycol – EG; 1,2 propane diol – 1,2PG; 1,3 propane diol – 1,3PG and glycerol – GL), were prepared by a sol-gel process starting from tetraethylorthosilicate (TEOS) and polyols, in acid catalysis. The resulting materials were studied by thermal analysis (in air and nitrogen), FTIR and solid state 29Si-NMR spectroscopy. These techniques evidenced the presence of polyols in the silica matrix both hydrogen bounded and chemically bounded in the silica network. The thermal analysis proves to be the most appropriate technique to evidence the organic chains linked in the matrix network and to follow the thermal evolution of the gels to the SiO2 matrix.
polyoxotungstate [ 21 ], silica supported peroxotungstate [ 22 , 23 ] and triphasic phosphotungstate [ 24 ] were used in typical works. Especially, the methods of grafting or tethering of active species onto the inner walls of mesoporous molecular sieves were
J Biol Chem 263 3194 3201 El-Rassy, H., Perrard, A., Pierre, A. C.: Behaviour of silica aerogel
transition metals into the framework of such materials (especially titanium) gives additional special catalytic properties [ 3 – 11 ]. Silica-titania materials (STM) possessing different compositions and physico-chemical characteristics are widely
silica gel so that a very slow reaction occurs with the formation of a sparingly soluble compound. When the concentration of this compound exceeds the solubility limits, crystals will be formed, while the main function of the gel is to control the flow of
Artificial pozzolanic cement pastes containing burnt clay with and without silica fume
Physicochemical, microstructural and thermal characteristics
, lowering heat of hydration, and thermal expansion [ 1 ]. Recently, the use of pozzolanic cement is increasing world-wide because it needs less energy for production. Early hydration reactions of Portland cement–silica fume blends were studied and
