In-Situ GISAXS Measurements on Films. In situ GISAXS measurements were conducted at the Austrian SAXS beamline at ELETTRA (Trieste, Italy). An X-ray beam with a wavelength of 0.77 Å (16.1 keV) and dimensions of 0.15 × 2.0 (vertical × horizontal in mm) was used, and a sample-to-detector distance of 2209 mm. This provided a q-range from 0.1 < q < 4.6 nm -1 . The Si wafer (2 x 5 mm) was mounted on a cradle with a resolution of 0.001°. The incident grazing angle was in the range 0.17 -0.18°. First, the 2D GISAXS patterns of the coated Si-wafer were acquired under environmental conditions (relative humidity ~ 30%, room temperature ~ 25°C) for 60 sec with a 1 sec delay between the 3 frames measured. For the measurements under defined relative humidity conditions, a humidity sensor was mounted inside a sample chamber with a diameter of 10 mm, and the humidity data was logged during the experiments. The humidity was adjusted by mixing a dry and humid air stream in specific ratios and injecting it into the sample chamber (dry-air unit from Oxford Instruments, Abingdon, U.K.; humid air stream was generated by bubbling dry air through a water reservoir).