Physics Colloquium: Probing Soft Material Properties at the Nanoscale
J. Alexander Liddle, Microsystems and Nanotechnology Division, Physical Measurement Laboratory, NIST
Soft materials are infinitely mutable, displaying extraordinary combinations of strength, toughness, and deformability. They are ubiquitous in nature and, as we improve our understanding of them, they are becoming more and more common in our daily lives. Unfortunately, extracting information about the nanoscale behavior of these materials is challenging, and novel techniques need to be developed. I will describe three projects that illustrate new approaches to probing soft material structure and properties with high resolution.
Carbon Nanotubes (CNTs) offer unparalleled strength, stiffness, and conductivity, and have therefore been a target of research in the world of nanocomposites. Determining structure-property relationships naturally relies on the accurate measurement of the structure. We have worked to develop high-resolution TEM tomography methods to provide quantitative morphological information on CNT composites and connect that to their microwave response. This can be used for process monitoring in a manufacturing environment.
DNA origami is a versatile platform that can assemble nanostructures with molecular precision. However, our understanding of the assembly pathway, and how it affects yield and perfection, is not complete. We have been using ensemble single-molecule fluorescence measurements of single-fold melt curves to investigate how the entropic costs of making this fold play a key role, both at thermal equilibrium and when kinetics dominate.
Single-molecule fluorescence imaging has had an enormous impact on biology, but has gained much less traction in materials science. This is partly a consequence of the difficulty in obtaining accurate measurements of fluorophore position – in materials, fluorophores are often in fixed orientations, which significantly complicates the measurement. However, if both position and orientation can be determined, they provide an excellent method of measuring nanoscale deformation in soft materials.
TEM image of CNT-epoxy composite.
Tuesday, October 16 at 3:15pm
Regents Hall, 109
3700 O St. NW