Morphogenesis of evaporation-induced self-assemblies of polypyrrole nanoparticles dispersed in a liquid medium.

Evaporation-induced self-assemblies (EISAs) with various morphologies were selectively fabricated by drying a solution containing polypyrrole nanoparticles. The morphogenesis of EISAs was strongly dependent upon the solvent evaporation rate and the nanoparticle concentration. In the case of fast evaporation, 2-D dendrites or pseudo 1-D dendrites were observed. When the liquid medium evaporated slowly, ring and spherulitic assemblies took place. Multiple rings could be created on a substrate surface under one single drop.