Liesegang rings engineered from charged nanoparticles.

Functionalized nanoparticles (NPs) serve as building blocks of self-organizing chemical patterns comprising periodic zones of nanoparticle precipitation. In contrast to ions, which underlie most pattern-forming chemical systems and whose properties cannot be readily modified, NPs allow for flexible adjustment of particle charges and/or material properties. In particular, changes in the particle charges control the precipitation behavior and ultimately the morphologies of the emerging patterns. The phenomenon of NP-based periodic precipitation is explained by reaction-diffusion modeling and can be used for the fractionation of NPs of different sizes.