Abstract

Time-resolved simultaneous experiments using synchrotron radiation have been realized to study in situ the concurrent formation of different templates in hierarchical porous thin films. Silica hybrid organic-inorganic films have been dip-coated and processed to obtain two porous nanostructures: spherical ordered mesopores templated by surfactant micelle, and cubic pores formed by crystallization of sodium chloride salts. The experimental setup has allowed following in real time the chemical-physical processes behind the formation of the two different templating agents. During deposition, the self-assembly and organization of the micelles have been studied by grazing incidence small-angle X-ray scattering while the crystallization of the salt template has been monitored by wide-angle X-ray scattering. After processing, the films have been further characterized by transmission electron microscopy, two-dimensional grazing incidence small-angle X-ray scattering and X-ray diffraction. The in situ analysis has revealed a short time delay between micelles and salt crystals formation; the micelles self-assemble and organize at the end of the first evaporation stage, when ethanol evaporates, while salt starts nucleating and growth only during the second stage, when water evaporation begins.

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