Supramolecular chemistry is an ideal means to program structural hierarchy in both polymer and composite materials, as it uses reversible interactions between atomically precise building blocks to create well-defined nano- to macroscopic structures. Simple synthetic adjustments in molecular composition can alter how polymers bind to one another in three-dimensional space, and this in turn can modulate the nanoscale morphology of the assembled material. Conversely, once assembled, these larger-scale structures can act as scaffolds that allow multiple supramolecular binders to behave as a collective unit. Because the shape of these larger length scale motifs can affect the ability of individual supramolecular motifs or polymer chains to coordinate their binding, material form at the nanoscale could potentially be used as a design handle to tune the supramolecular groups’ collective bodn strength. Understanding how to control structural hierarchy in this manner therefore necessitates the development of a synthetic building block whose nanoscale morphology can be tuned independently of the individual supramolecular binding groups themselves. We have recently demonstrated a new polymer brush-particle building block capable of directed assembly via complementary hydrogen bonding motifs, called the Nanocomposite Tecton (NCT). NCTs consist of an inorganic nanoparticle core coated with a dense polymer brush, where each polymer chain terminates in a supramolecular bonding group; interparticle interactions drive particle assembly by creating dynamic nanoscopic bonds consisting of multiple supramolecular linkages. NCT assembly is distinct from other materials synthesis methods that use hydrogen bonding motifs, as each NCT-NCT connection consists of multiple supramolecular interactions that behave collectively not because individual groups are closely linked via covalent bonds, but rather because they are geometrically confined to a localized volume at the NCT surface. An NCT’s nanoscale geometry therefore has a strong influence on its assembly behavior, and can be used to tune NCT-NCT bond strength <i>without</i> changing molecule-molecule bond strength. Here we show how nanoscale structure can be used to manipulate material morphology in a holistic manner, where structural features at the molecular, nano, and mesoscopic length scales influence one another in a programmable fashion, and each can be used to dictate material behavior.

System-level structural control of self-assembled nanoparticle polymer composites

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.