Controllable macroporous morphology of spontaneously grown silica films from a sol-gel solution containing a Pluronic surfactant

Accessibility and specific surface area are important factors related to the functions and efficiencies of thin films that act as adsorbents, supports for catalysts, and so on. Therefore, controlling the surface morphology or macro porosity has attracted a great deal of attention. In this work, a spontaneous silica film growth process in a sol-gel solution was studied by observing electron microscopy images as well as by using UV-VIS spectroscopy and surface roughness measurements. As a result, a macroporous silica film was formed in a sol-gel solution containing Pluronic P123 as a structure-directing agent. Furthermore, a preparation of macroporous silica films that have different morphologies was attained by using different Pluronic surfactants and inorganic salts. Some films had a micrometer order rod-like structure, and others had a reticular structure composed of a concatenation of short rod-like nanoparticles. Nitrogen adsorption desorption isotherms were measured for silica deposits that formed during film growth in the sol-gel solution to discuss the characteristics of the silica thin films.