(767d) Fabrication of Reinforced Porous Nanocomposites With Silica Nanorods and Nanospheres

The compromise in strength associated with increasing porosity is a general dilemma for porous materials. In this study, we present a strategy for fabricating porous materials of improved strength without compromising either the porosity or the purity. Porous nanocomposites created using either silica nanorods or nanospheres were prepared through freeze casting aqueous suspensions of these materials. It was found that replacing silica nanospheres with silica nanorods substantially improved the mechanical strength (e.g. a factor of six for nanorods with aspect ratio of 12) of the resulting composite while maintain its porosity. Silica nanorods with fixed diameter but variable length were synthesized using a one-pot method, and the strengthening effect with nanorods of different aspect ratios was investigated. The interaction between rod-like particles and the solidification fronts during freeze casting will be quantitatively discussed, and the formation and evolution of porous microstructures with nanorods explained. Because this strategy is not believed to be material specific, it should be applicable to a range of materials.