Simulating the Resonant Soft X-Ray Scattering of Realistic Multiblock Copolymer Morphologies

Block copolymers are a class of soft materials that can self-assemble into mesocrystals, with applications ranging from polymer electrolyte membranes for batteries to drug-eluting coatings for biomedical devices. The detailed structure of multiblock copolymers is challenging to characterize due to the lack of chemical specificity of conventional techniques such as hard X-ray scattering. A technique called resonant soft X-ray scattering (RSoXS) leverages the unique absorption spectra of different chemical components in multi-material systems to produce scattering patterns with chemical sensitivity. Block copolymers that phase-separate into periodic structures are ideal model systems to study with RSoXS simulation tools because their scattering patterns are simple to predict. We use a resonant soft X-ray scattering simulation software (Cy-RSoXS) to study the complex structure of multiblock copolymers. We have developed Python-based scripts to create voxelized simulations of cylinders on a hexagonal lattice, a common block copolymer structure. We then implemented algorithms to simulate real samples in which the cylinders have varying radii and spacing, or the interface between different blocks exhibits a compositional gradient. The effect of these realistic features manifest into changes in the scattering pattern, such as changes in scattering intensity, peak location and peak shape. Cy-RSoXS gives us the capability to study these effects, understand phase purity, and develop more robust process-structure-property relationships. The simulation platform we have developed will enable researchers studying block copolymers with RSoXS to more accurately predict the energy-dependent scattering of realistic multiblock copolymers.