Polymer morphology measurement by Polarized Resonant Soft X-ray Scattering

In many polymers, the connection between morphology and performance is complex, and conventional materials structure measurements are not sufficient to provide a predictive structural model. Nanoscale variations in molecular orientation and composition, particularly in amorphous regions, are thought to be critical, but few techniques can probe them. I will describe our approach to polarized resonant soft X-ray scattering (P-RSoXS), which combines principles of soft X-ray spectroscopy, small-angle scattering, real-space imaging, and molecular simulation to produce a molecular scale structure measurement for soft materials and complex fluids. I will provide a complete description of our newly-constructed P-RSoXS measurement station at NIST beamlines of the National Synchrotron Light Source II. Results from model systems including commodity plastics, block copolymers, and semiconducting polymers will be discussed. An emphasis will be placed on connections between P-RSoXS and small angle neutron scattering (SANS), especially similarities in contrast variation approaches. I will conclude with our progress toward a forward-simulation framework that describes scattering length density at the nanoscale as a 3D tensor. Results from this approach provide previously inaccessible orientation information that impacts properties across a range of important material functions.