High-resolution grazing incidence small angle X-ray scattering:: Investigation of micrometer sized structured polymer films

While bulk samples are routinely probed by small angle X-ray scattering (SAXS) and ultra-small angle X-ray scattering (USAXS), the grazing incidence geometry enables the necessary surface sensitivity to probe structured polymer films. Based on examples of polymer blend films of polystyrene and poly-n-butylacrylate as well as polymeric nano-structures of polydimethylsiloxane the present possibilities of high-resolution grazing incidence small angle X-ray scattering (GISAXS) are demonstrated. Three different GISAXS resolutions, denoted with relaxed, high and ultra-high resolution are presented. Thus GISAXS experimentally enables the determination of a large range of length scale varying from the molecular level (nanometer) to several micrometers. This development allows for an overlap with optical techniques combined with the very high sensitivity of the grazing incidence geometry. The impact of an enhanced surface sensitivity is pictured by probing the polymer structures at different depths. In addition, the possibility of determining buried structures is addressed. Depending on the characteristic structure of the thin film a simulation of the two-dimensional GISAXS pattern is important to determine the influence of structural key parameters. Therefore GISAXS pattern simulations are shown to picture sample induced limiting factors of the detection of large scale structures.