Controlling the macroscopic properties of self-assembled structures by designing the composition of their building blocks at the atomic level is an ongoing challenge for nanoscience. Towards this goal, Wen-Bin Zhang, Yiwen Li, Stephen Cheng and colleagues now report preparing self-assembled polymeric nanoparticles that possess a precisely defined primary structure and also a predictable macroscopic morphology and chemical properties.
The researchers — who are based at the University of Akron, Texas State University, CNRS-Université de Strasbourg and Peking University — start with an azido-functionalized polystyrene to which they attach a silsequioxane cage bearing both an azido and an aldehyde group. Through successive click chemistry reactions, they then elongate the polymeric chain, which introduces other silsequioxane cages. Moreover, the backbone can be made either linear or branched by installing small linkers. The final, giant molecule can be as large as ∼20 nm. In the bulk, the molecules self-assemble to produce a variety of ordered supramolecular structures and a variety of surface chemistries, depending on the length of the chains, the functionalization of the silsequioxane cages and the branching of the polymer backbone.