Design of a highly ordered and uniform porous structure with multisized pores in film and particle forms using a template-driven self-assembly technique

A highly ordered arrangement of pores with multiple sizes in film and particle forms was successfully prepared using the dip-coating and spray-drying methods, respectively. The template-driven self-assembly technique was effective when a combination of 5 nm silica (as a model of an inorganic nanoparticle) and two different sizes of monodispersed polystyrene (PS) spheres (as models of the template) were self-assembled to produce a composite silica/PS template. Heat treatment was then used to remove the PS, which produced the porous particle. A material with spherical pores in an “art-design” organization was produced. The size of the pores (large pore: 100–1000 nm; small pore: 30–200 nm) could be controlled simply by adjusting the PS size. Sufficient numbers of large/small pores made it possible to produce a material of ultralow density with an ultralow refractive index, because the multiple pores allocated free space, all of which was confirmed by calculation.