experiments for PEI residues were performed using the GANESHA-SAXS/WAXS instrument from SAXS-LAB (Denmark) equipped with a 100XL+ microfocus sealed X-ray tube CuKα radiation (λ = 1.54 Å) (Rigaku, Japan) with Kirkpatrick-Baez focusing mirror system and a two-dimensional 300k Pilatus detector from Dectris (Switzerland). The measurements were carried out at two distances (50 mm and 350 mm) by varying the distance between sample holder and detector.