Pseudoboehmite Nanorod–Polymethylsilsesquioxane Monoliths Formed by Colloidal Gelation

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 greater amounts of MTMS led to coarsening of the skeleton and strengthening of the skeletal structure, and the monoliths got water resistance. When a dispersion of zirconium oxide nanoparticles and MTMS was used as a starting material, a macroporous monolith was also obtained by the same simple process. The 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. Due to the development of material chemistry, colloidal dispersions having various shapes and compositions are becoming available as products. Based on this mechanism, it is expected to be feasible to fabricate various porous monoliths with characteristic morphologies and properties depending on the colloid.