Structural changes during drying of nano-aggregated inks

With increasing concentration above the overlap concentration, nanoaggregates become entwined and structural information at scales larger than an emergent mesh size are obscured. When observed in small-angle scattering, this is termed structural screening and is observed in the low-q regime. While observed as a function of concentration in solutions, structural screening is also apparent on relatively thick dried nano-aggregate layers such as in a dried ink plaque or a paint chip. In addition to this screening effect, emergent micron-scale network structures are often observed. These micron-scale structures may be responsible for optical properties in pigments and mechanical properties in reinforced elastomers. In investigating thin printed layers of nanoparticles, it was found that the impact of structural screening on the measurement of aggregate structures can be minimized in thin samples such as inkjet-printed layers of nano-aggregates with thicknesses on the order of less than 100 times the nano-aggregate size.