Polarized Resonant Soft X-Ray Scattering (P-RSoXS) As a Tool to Measure Structure at Crystalline-Amorphous Interfaces of Semi-Crystalline Polymers.

The structure of the amorphous phase has a significant influence on the macroscopic properties of semi-crystalline polymers. However, the exact structure of the amorphous region can be difficult to quantify, given its less-ordered structure and various chain connectivities. Therefore, it is difficult to define unambiguous processing-structure-function relationships for these systems. In this work, we show the capabilities and potential of polarized resonant soft X-ray scattering (p-RSoXS) to measure chain density and orientation at the crystalline-amorphous interface in polylactic acid (PLA). p-RSoXS exploits the chemically and directionally sensitive interaction between polarized X-rays and oriented chemical bonds, enhancing scattering from specific bond-bond correlations. We use a forward-scattering GPU-accelerated simulation, CyRSoXS, based on high-resolution TEM imaging to identify a real-space model that produces a combination of compositional and orientational scattering that is consistent with experiment. This approach allows us to measure the direction, spatial extent, and magnitude of orientation in polymer chains at amorphous-crystalline interfaces to provide insight into the effect of processing conditions on the structure and properties of semi-crystalline polymers.