The addition of a trifunctional silicon alkoxide methyltrimethoxysilane (MTMS) to aluminum oxide hydroxide pseudoboehmite nanorod (PBNR) aqueous dispersions resulted in adhesion between the PBNR colloids to form macroporous monoliths. The use of higher amounts of MTMS led to coarsening of the skeletons and strengthening of the skeletal structures, giving the monoliths water resistance. When a dispersion of zirconium oxide nanoparticles and MTMS was used as the starting material, a macroporous monolith was also obtained by the same simple process. Colloidal gelation occurs because the silanol moiety is more likely to react with the colloid surface of ceramic materials than with other silanols derived from MTMS and their oligomer. With the development of materials chemistry, colloidal dispersions with various shapes and compositions are becoming available as products. The present mechanism is expected to make fabrication of various porous monoliths with characteristic morphologies and properties feasible depending on the colloid made as the starting material.
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