Three-dimensional structure of a sintered macroporous silica gel

Three-dimensional (3D) macroporous morphology of a silica gel, formed as a result of the phase separation parallel to the sol-gel transition, was obse rved in real space by laser scanning confocal microscopy. The 3D image of t he silica gel skeleton that was sintered into full dense pure silica glasse s clearly demonstrated that the gel skeleton is continuous and interconnect ed in 3D space. The interface between the gel skeleton and the macropore wa s characterized in terms of interfacial curvatures. It was found that a lar ge portion of the interface is hyperbolic, which is also found in a phase-s eparated structure of a binary polymer mixture developed during the spinoda l decomposition(SD). Comparison was made in terms of the probability densit ies of the interfacial curvatures between the silica gel and a polymer mixt ure having an identical phase volume fraction to one of the phases. Althoug h the probability density distribution of the mean curvature, H, representi ng geometrical characteristics of the interface, was symmetrical about zero for the silica gel and that for the polymer mixture was asymmetrical, over all features of the interface shape were similar. This finding supports the idea that the 3D morphology of the macroporous silica gel is formed via SD .