Chain-Length Effect on Binary Superlattices of Polymer-Tethered Nanoparticles

Binary inorganic nanoparticles (NPs) can be assembled into various types of superlattices depending on the size ratio, shape, and interparticle potential, which may tailor mechanical, optical and electronic properties. Here, polymer-stabilized gold NPs are assembled into binary nanoparticle superlattices (BNSLs) and their structures were precisely controlled by tuning the size ratio of NPs as well as chain length of polymer ligands. Typically, binary gold NPs with short-chain polymer ligands showed the phase behaviors of hard-sphere colloids. By contrast, ones with long-chain polymer ligands showed the phase behavior of soft-sphere binary colloids. Interestingly, mixed binary NPs with short-chain and long-chain polymer ligands showed unnatural binary NPs superlattices in thin film, in which small NPs are contained in octahedral voids of regular HCP lattice. Our finding can be further extended to other types of functional NPs, which may tune the various properties for devices