EFFECTS OF AGING AND SOLVENT EXCHANGE ON PORE STRUCTURE OF SILICA-GELS WITH INTERCONNECTED MACROPORES

For silica gels with interconnected macropore morphology, the pore structure in the micrometer and nanometer size ranges has been investigated. The pore size distribution of dried gel in nanometer-range was influenced by the conditions of aging and solvent exchange treatments in the wet state, whereas only the drying behavior of macropore structure was affected by those conditions. These variations are explained by the occurrence of swelling and microscopic phase separation, the degree of which is determined by the solvent quality, of the gel networks. Small-angle X-ray scattering results confirmed the structural change in the wet state. The difference in thermal evolution behavior of nanopore structure with solvent exchange was also examined in relation to the difference in size of the structural unit.