Professor Robert Macfarlane
Massachusetts Institute of Technology
Hosted by Professor KiBum Lee and Professor Jason Zhang
Tuesday November 13, 2018
11:00AM, CCB* Auditorium
*New Chemistry and Chemical Biology Building
"Systems-Level Control of Structural Hierarchy"
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 manipulating the thermodynamics of chemical bonding between 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. Here, we will discuss two different methods to synthesize materials in a systems-focused approach that mimics nature's ability to general complex structural motifs across a wide range of size regimes. The first uses nanoscale design handles to deliberately control the multivalent assembly of particle-grafted supramolecular binding moieties, where control over both molecular and nanostructure of material building blocks is then used to manipulate the mesoscale structure of the resulting materials. The second uses macroscopic interfaces to dictate the assembly behavior of DNA-grafted nanoparticles, generating superlattice architectures with controlled sizes, shapes, and orientations. Together, these techniques allow for systems-level approaches to materials design, expanding our ability to program hierarchical ordering at the molecular, nano, and macroscale simultaneously.
~Coffee/tea will be served prior to lecture~