Structural hierarchy is a powerful design concept where specific geometric motifs are used to influence material structure across multiple size regimes. These complex levels of organization are typically achieved in the laboratory by conceptually breaking a material down into the smallest components that can be manipulated (e.g. individual molecules, macromolecules, or nanoparticles), and using the geometric information in those components to control how they build up into larger length scale patterns. Conversely, complex assemblies in natural systems are commonly achieved through a more holistic approach where assembly behaviors at the molecular, nano, and macroscopic scales are interlinked. This means that not only does structural information contained in molecular building blocks filter upwards to dictate material form at the nano to macroscopic levels, but also that the environment created by the larger length scale features can affect the behavior of individual components. Despite the potential of such a method of materials design, our ability to mimic these natural processes and holistically program structural hierarchy in artificial materials is still severely underdeveloped. Here, we demonstrate a metal nanoparticle-based building block called a “Nanocomposite Tecton (NCT)” that enables nanoscale geometry to function as a design handle to directly modulate the assembly behavior of a collection of supramolecular binding groups. The ability to use nanoscale geometry to modify molecular behavior allows a single set of NCTs to access different nanoscale bonding valencies, resulting in different mesoscale particle arrangements and different supramolecular bond strengths. The formation of distinct hierarchical structures at the nano and mesoscale is therefore both a consequence of and a direct influence on the molecular binding events that drive assembly. The use of nanoscale geometry to dictate supramolecular binding provides a major step forward in understanding how the assembly of hierarchically ordered artificial materials can be done in a holistic manner across multiple size regimes.

System-level control of structural hierarchy

2019 Spring National Meeting

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