Anomalous Hydrodynamic Size Distributions of Alkylamine/Alkylacid-Encapsulated Silver Nanocolloids: Implications for Printing Ultrafine Conductive Patterns

Alkylamine/alkylacid-encapsulated silver nanocolloids (amac-AgNCs) present a unique coexistence of their dispersion stability as nanocolloids and fusion reactivity after drying. This feature is useful for the printing-based production of ultrafine conductive patterns, although the origin is not yet understood. Here, we demonstrated the effects of the addition of a protic solvent on the colloidal states of amac-AgNCs as revealed by confocal dynamic light scattering. We observed an abrupt change in the hydrodynamic size distribution of amac-AgNCs depending on the methanol concentration. When the concentration of methanol exceeded 7 vol %, the nanoparticle size distribution exhibited a sudden and considerable broadening. Similar effects were observed with other protic solvents but not with aprotic polar solvents. We suggest that the feature could be ascribed to the solvation shell effect, which is responsible for the instability of nanoparticle aggregation. These findings provide a way to control the peculiar colloidal states and dispersion stability of the metal nanocolloids, allowing a major step forward in printing ultrafine conductive patterns with the metal nanocolloids.