A new process for coating a mesoporous silica gel with a mixture of the grafting reagents para-aminophenyltrimethoxysilane and phenyltrimethoxysilane is thoroughly analyzed. The dilution of para-aminophenylsilane with phenylsilane at different ratios allows the density of the functional amino groups present on the silica surface to be controlled, while keeping constant the overall number of grafts. Furthermore, the choice of a rigid linker prevents undesirable interactions between the active function and the inorganic support that could alter the function reactivity. This simple and new method, which results in the improvement of the dispersion of a functionality in a one-pot synthesis, could be particularly interesting in the field of supported catalysis and molecular recognition. The dispersion of the functional groups of the synthesized hybrid solids is investigated using a pyrene derivative covalently linked to the free amino groups of the para-aminophenylsilanes by analyzing the excimer and monomer fluorescence properties of the probe.

Many new materials are now allowing new properties thanks to nanotechnology because this domain of physics gives possibilities to optimize targeted properties even if these materials react in very various influential parameters. Architectural, automotive, bone pathologies, environment, display applications are some concerned domains. The sol-gel process is a method allowing the realisation of coats at ambiant temperature, thus it is possible to realize Liquid Crystal Display (LCD), water-repellent coatings on privacy glass, antireflective coatings, hydrophobic or hydrophilic surfaces, bone tissue regeneration. In this study, the purpose is to show the thermal influence on a covered glass with a complex hybrid sol-gel solution. This coated glass is going to change color from red to orange under the heat influence. This color change effect comes from the evolution of various compounds organizations then/or from their loss during the degassing sequence. We show in spite of the complexity of the process that the responsible is mainly the organic dye. Thus the structure of the heated glass at 250 degrees C looks radically different than the heated one at 350 degrees C. SEM measurement allows to identify the surface compositions and to determine the elementary composition along the sample's cross section. TGA is used to justify a mass loss when samples are annealed. UV/Visible measurement is realized by two methods: in-line transmission to evaluate luminous flux and thus give colorimetric dot in the normalized CIE diagram and diffuse transmission to observe the size influence of the pigments. Infrared Reflectivity allows to evaluate the influence of species on the structure and to better target the nature of the lost compounds during annealing. TEM measurement proves that the obtained iron particles are nano rods for both samples.

Thickness shear mode transducer techniques using AT-cut quartz crystal can be used to measure viscoelastic parameters of soft materials (gels, colloidal suspensions œ) during their formation. Today the control of hybrid materials synthesis and evolution has a great interest, particularly for biomedical applications such as drug delivery. With those materials, a challenge is to obtain new structures constituted by interpenetrating organic- inorganic polymers networks (IPN) to get novel therapeutic behaviours. In this paper, the monitoring of ultrasonic shear waves propagation in the material at 6 MHz is presented for different thermosensible hybrid (poly-N-isopropylacrylamide (PNIPAM) - silica). We show that at a mesoscopic scale it is possible to analyze mechanical interactions between different networks related to chemical bounds. The network evolution observed with our technique is in good agreement with the Fourier transform infrared analysis of NIPAM polymerization. As shown in previous work for silica gels, a precursor characteristic time of gelation process (in liquid phase) can be determined to describe the polymerization kinetic. By its nondestructive character and its simplicity of measurement, this technique allows an online optimization of new hybrid materials.