Laterally Inhomogeneous Self-Ordered Structures on Surfaces Investigated by GISAXS Microtomography

Grazing-incidence small-angle x-ray scattering (GISAXS) is a standard tool for the analysis of surfaces and thin layers containing nanometer-sized structures. In order to obtain a two-dimensional map of their local morphology, we performed GISAXS microtomography on dried drops of colloidal suspensions. In particular, we investigated the self-organization of drying suspensions of TiO2 on polyethylene surfaces. Hierarchically structured titania films and their mesoporous structure on the nanoscale have a large variety of applications, e. g., in photovoltaics, photocatalysis, and gas sensing. They are prepared by combining sol-gel chemistry with an amphiphilic diblock copolymere as a structure-directing agent. The sample presented here is a dried drop of nanostructured titania (TiO2), consisting of a sponge-like structure with an expected pore size of 30 40 nm. Figure 1(a) shows an optical micrograph of this laterally inhomogeneous sample. Prior to depositing the drop, the Si substrate was spin coated with the same solution.