Scanning electron microscopy (SEM) imaging reveals that all SBPs have a cauliflower-shaped morphology typically observed for materials formed via point-nucleation in irreversible coupling reactions, with particle sizes in the range of 50-100 µm (Figures ). Powder X-ray diffraction (PXRD) patterns show that these materials are completely amorphous, as expected for products of palladium-catalyzed irreversible C-C coupling reactions (Figure ).