2, Korea University of Science and Technology (UST), Daejeon, , Korea (the Republic of)
It is well known that sand bed has numerous voids inside and the voids are much smaller than the sand particles. Therefore, the sand bed has been utilized as filtration media for a long time and it is still used for pre-treatment of water in modern industries. This study provides a new principle for fabrication of nano voids using nanoparticles, in the similar way of conventional sand bed. Polystyrene nanoparticles with various sizes of 150, 60 and 24 nm have been embedded in the pores of the anodic aluminum oxide (AAO) template, so that voids between the nanoparticles could be made in nano scale. These voids can be considered as effective pores for filtration or separation. By this method, a lot of nano voids could be fabricated on a large area (diameter of template : 25 mm) with a simple process. Since overall size of the voids is expected to be much smaller than that of the nanoparticles, this principle is expected to have effective pore size of a few nanometers. And as long as the sizes of the nanoparticles are uniform, size of the voids could be quite uniform also. Furthermore, we treated the surfaces of the nanoparticles with arginine/phenylalanine peptide ((RF)4), so that the particles could be electrically charged. In order to evaluate embedment of the nanoparticles, hydraulic experiment was performed with the substrate and pressure drops were measured. The pressure drops became higher as smaller nanoparticles were embedded, which means that smaller voids were made inside.