大型放射光施設 SPring-8

Speaker: Dean M. DeLongchamp

Language: English

Affiliation: Material Measurement Laboratory, National Institute of Standards and Technology (NIST)

Title: Polarized resonant soft X-ray scattering for nanoscale molecular orientation measurements in polymers

Abstract:
Orientation and conformation in nanoscale amorphous regions often dominate the properties of polymeric materials. Robust correlations between structure in these amorphous regions and important properties are not well developed due to a lack of measurements with high spatial resolution and a sensitivity to molecular orientation. I will describe our approach to solving this issue using polarized resonant soft X-ray scattering (P-RSoXS), which combines principles of soft X-ray spectroscopy, small-angle scattering, and data fusion with real-space imaging to produce a molecular scale structure measurement for soft materials.

I will focus on recent results from polarized resonant soft X-ray scattering (P-RSoXS) measurements of semicrystalline polymers, nanocomposites, and block copolymers. Our analysis approach extracts molecular orientation details with a spatial resolution of ≈ 2 nm or smaller. This work is now accelerated by a powerful software code base using parallel computation across graphics processing units (GPUs) for the forward-simulation of P-RSoXS patterns. Our approaches now include data fusion with real space measurements such as atomic force microscopy and transmission electron microscopy, as well as direct fitting of experimental P-RSoXS data with simulation results, enabling the extraction of quantitative nanoscale orientation landscapes describing never-before-measured radial chain orientation distributions near interfaces in glassy regions of polymer-grafted nanocomposites and block copolymers. These new P- RSoXS capabilities show great promise for informing and guiding the processing and synthetic design of soft materials.