Self-assembly of nanoparticles in polymer-like chains bears a strong similarity to polymerization reactions, in which monomer units are brought together by directional noncovalent interactions. Based on this similarity, the molecular concepts of polymer chemistry can be applied to achieve controllable nanoparticle assembly. On the other hand, the ability to visualize nanoparticle assemblies and to exploit characterization tools used in nanoscience offers a unique way to study polymerization reactions. Here we explore this twofold strategy for an exemplary system including the self-assembly of bifunctional metal nanorods in the presence of monofunctional nanoparticles (chain stoppers). The approach provided insight into the polymerization kinetics, side reactions, the distribution of species in the system, and the design rules for the synthesis of molecular chain stoppers
