Differential scanning calorimetry and X-ray diffraction study of water confined in silica gel for several levels of hydration

Differential scanning calorimetry (DSC) and X-ray scattering measurements on water confined in silica gel is studied for several levels of hydration at room temperature and down to 77 K. The DSC analysis of water confined in silica gel in function of the level of hydration shows that the solidification of water inside the pore is sensitive to the pore opening but the fusion is closely related to the curve of the pore. The X-ray pair correlation function showed the presence of a distorted tetrahedral-like hydrogen-bonded network of water characterized by the peaks at ~2.8, ~4.1 and ~4.9 Å. This distortion is caused by the competition between confinement effect and silica-water interaction. To eliminate the contribution of the water-silica gel interaction we have determined the structure of confined water by subtraction of the feebly hydrated silica gel from that strongly hydrated sample. The pair correlation function of extracted water show an oxygen-oxygen correlation at 3.8 Å. A similar peak is observed in the case of water confined in polyHEMA, in charcoal and at vicinity of myoglobin

Étude des modifications structurales de l'eau confinée dans le gel de silice

Les modifications structurales de l'eau confinée dans le gel de silice en poudre en fonction du taux d'hydratation sont étudiées par calorimétrie différentielle à balayage et par diffusion des rayons X. L'analyse thermique par DSC a permis de montrer que pour les faibles taux d'hydratation ($\le 50\%$) l'eau est complètement confinée dans les pores alors que pour les forts taux d'hydratation ($>50\%$) l'eau se trouve aussi bien dans les pores qu'autour des grains de la silice. L'apparition de la glace cubique lors du refroidissement de l'eau confinée dans le gel de silice prouve que l'interaction eau-silice ne peut être négligée lors de la détermination du signal de l'eau. L'extraction du signal, diffusé uniquement par l'eau confinée, à partir des intensités diffusées par le gel de silice à deux taux d'hydratation distincts, révèle dans les fonctions de corrélation de paire un pic à 3.7Å qui ne peut être attribué qu'à une corrélation oxygène-oxygène inexistante dans l'eau massique et résultant de la déformation du réseau tétraédrique des molécules d'eau sous l'effet du confinement et de la proximité d'une surface

Analysis of in vitro reaction layers formed on 48S4 glass for applications in biomaterial field

International audienc

X-ray and neutron scattering studies of the structure of hyperquenched glassy water

International audienceX-ray and neutron diffraction measurements were performed on glassy water prepared by rapid cooling of water droplets on a cryoplate. Structure factors and radial distribution functions were found to be nearly identical to those obtained from amorphous ice formed either by vapor deposition onto substrates cooled at 77 K or after heating the high-density amorphous ice

Investigation of the surface reactivity of a sol-gel derived glass in the ternary system SiO2-CaO-P2O5

Applied Surface Science, 2008, 254, 7386 – 739

Effect of aging temperature on the structure, pore morphology and bioactivity of new sol–gel synthesized bioglass

International audienceno abstrac

Structural and comparative study of water confined in a mesoporous bioglass by X-ray total scattering

International audienceThe structural properties of water confined in two silica matrices characterised by well-controlled organised porosity with a narrow pore size distributioni)a new mesoporous bioactive glass (MBG 92S6) andii)SiO2 MCM-41 were studied using laboratory total X-ray scattering coupled to molecular pair distribution function (PDF). The PDF analysis shows that the hydrophilic/hydrophobic character of the water-bioglass interface affects the structural properties of the confined water in the same way as water confined in different mesoporous matrices presenting an intermediate hydrophilic and hydrophobic interface regardless of their pore size and distribution. We also compare the effect of the confinement inside MBG 92S6 and different mesoporous hydrophilic and hydrophobic silica matrices. We show that the pore surface properties have a stronger influence on the structural organisation of the confined water than the pore size distribution

Synthesis and “in vitro” characterization of melt derived 47S CaO-P2O5-SiO2-NaO bioactive glass

Ceramics - Silikaty, 2008, 3, 121 – 12