Small angle neutron scattering (SANS) and physisorption (N2) experiments have been used to study the influence of aging on the structure of dried gels. These gels were aged for various times at elevated temperature (80°C) or under the addition of catalytic quantities of fluorine. Both the porous kernel and the pores within the kernel grow during aging. However, addition of fluorine or aging at 80°C results in different pore structures, although the same ultimate particles size is reached in both cases. Owing to slit-like or isolated pores obtained in the fluorine aged sample, the physisorption and SANS results did not coincide while the 80°C aged gels showed reasonable agreement between both techniques. Although the structure of the porous silica was distorted by wetting, contrast variation experiments with a H2O/D2O mixture confirmed the scattering by pores. This scattering is replaced by scattering from the surface of the particles.
|Name||Studies in Surface Science and Catalysis|
|Conference||conference; IUPAC Symposium on the Characterisation of Porous Solids ; 3 (Marseille) : 1993.05.09-12; 1993-05-09; 1993-05-12|
|Period||9/05/93 → 12/05/93|
|Other||IUPAC Symposium on the Characterisation of Porous Solids ; 3 (Marseille) : 1993.05.09-12|