Large-Scale Patterning of TiO2 Nano Powders Using Micro Molds

Abstract

For the fabrication of ceramic micro-scale patterns over a wide area, the Micro-molding in Capillaries MIMIC method is can be used by applying low solid loading colloidal suspensions of nanopowders. However, to uniformly form thick films from low solids loading suspensions, it is necessary that the additional spontaneous process of concentrating the suspensions in the molds occurs and is successfully accomplished, after the ordinary MIMIC process caused by capillary action. This concentration of suspension occurs as a result of inflow of the suspension from the entrance along with solvent evaporation from the exit of the mold. Therefore, the suspension preparation is important in order that the particles flow in due to the flow of the solvent. In this study, we determined the required condition of the suspension preparation by fabricating films from aqueous and ethanolbased suspensions of TiO2 nanopowders. By comparing the uniformity of the fabricated films and the particle distributions of the suspensions, it was found that the condition required for uniform patterning over a wide area is to disperse the nanoparticles into their primary size.

Nanosized TiO2 Photocatalyst Powder via Sol‐Gel Method: Effect of Hydrolysis Degree on Powder Properties

“…It is worthy to note that the particle size measured from this analysis was quite big in size due to the possibility that powder's agglomerates were measured instead of individual particles. In fact, most particles were dispersed into a primary size in aqueous suspension [23]. In addition, small particles tend to agglomerate due to its high surface energy to attract other particles to combine together and form large primary particles.…”

Microfluidically Patterned Dome‐Shaped Photonic Colloidal Crystals Exhibiting Structural Colors with Low Angle Dependency

“…[17,19,20] The effect of the centrifugal pressure on crystallization is smaller than that of convection because the difference in the densities of polystyrene (1.05 g cm −3 ) and water (1.00 g cm −3 ) is small. Because the solvent evaporates only near the end of the microchannel, the colloidal suspension does not crystallize in the middle of the microchannel or in its branches.…”

“…At the end of the microchannels, convection driven by the evaporation of the solvent is the dominant phenomenon. [17,19,20] The effect of the centrifugal pressure on crystallization is smaller than that of convection because the difference in the densities of polystyrene (1.05 g cm −3 ) and water (1.00 g cm −3 ) is small.…”

Micrometer and nanometer-scale parallel patterning of ceramic and organic–inorganic hybrid materials

“…A requirement is that the nanoparticle suspension should be well dispersed into primary particles. 143 To increase the penetration length, Ahn et al proposed vacuum-assisted filling of channels. Moreover, slowing down the drying process inside the channels improves the packing efficiency of suspension particles.…”