Controlling shape and dimensions of pores in organic-inorganic films: nanocubes and nanospheres

Porous organic-inorganic hybrid films with well defined pore shape and dimension have been obtained via a salt-template route. Sodium chloride precipitates during film deposition as templating for cubic shape pores; combining this salt-template route with controlled phase separation, pores of spherical shape in the same film have been also obtained. The dimensions of the nanocubes and nanospheres are in the 20-200 nm range and can be modulated through the film processing conditions. We have systematically investigated the effect of precursor solution aging and surfactant concentration on the porous film structure using infrared spectroscopy, spectroscopic ellipsometry, X-ray diffraction, Raman imaging, atomic force microscopy and transmission electron microscopy. Only a very specific combination of different synthesis parameters, such as surfactant concentration and aging of the precursor solution, allows the formation of the pore templates.