“…In the solid state, however, polymer 6 is nonfluorescent. X-ray diffractions ( Figure 2 b), obtained with a Cu Kα source, however, display a broad diffraction pattern, around 20–25°, indicating stacking of the aromatic planes with a large 4–4.5 Å spacing, similar to the observations reported by Song et al 18 Since we observed this difference in stacking of our polymer before and after casting ( Figure 2 c,d), we carried out small-angle X-ray scattering/wide-angle X-ray scattering (SAXS/WAXS) measurements to elucidate the possible morphological changes. For this purpose, analyses using synchrotron X-rays were performed on the PPDI powders before casting (i.e., unprocessed PPDI) and after solubilization of the polymer and evaporation of the solvent (i.e., processed PPDI).…”