Showing papers by "R. Joseph Kline published in 2021"
TL;DR: In this article, the authors present the design and performance of a polarized Resonant Soft X-ray Scattering (RSoXS) station for soft matter characterization built by the National Institute of Standards and Technology (NIST) at the National Synchrotron Light Source-II (NSLS-II).
Abstract: We present the design and performance of a polarized Resonant Soft X-ray Scattering (RSoXS) station for soft matter characterization built by the National Institute of Standards and Technology (NIST) at the National Synchrotron Light Source-II (NSLS-II). The RSoXS station is located within the Spectroscopy Soft and Tender (SST) beamline suite at NSLS-II located in Brookhaven National Laboratory, New York. Numerous elements of the RSoXS station were designed for optimal performance for measurements on soft matter systems, where it is of critical importance to minimize beam damage and maximize collection efficiency of polarized X-rays. These elements include a novel optical design, sample manipulator and sample environments, as well as detector setups. Finally, we will report the performance of the measurement station, including energy resolution, higher harmonic content and suppression methods, the extent and mitigation of the carbon absorption dip on optics, and the range of polarizations available from the elliptically polarized undulator source.
6 citations
TL;DR: In this article, the authors investigate how specific interactions between the substrate and BCPs with varying substrate affinity impact the interfacial width between polymer components and find that the interface width decays toward equilibrium moving away from the substrate, with the decay rate being a function of film thickness below a critical limit.
Abstract: Interactions between polymers and surfaces can be used to influence properties including mechanical performance in nanocomposites, the glass transition temperature, and the orientation of thin film block copolymers (BCPs). In this work we investigate how specific interactions between the substrate and BCPs with varying substrate affinity impact the interfacial width between polymer components. The interface width is generally assumed to be a function of the BCP properties and independent of the surface affinity or substrate proximity. Using resonant soft X-ray reflectivity the optical constants of the film can be controlled by changing the incident energy, thereby varying the depth sensitivity of the measurement. Resonant soft X-ray reflectivity measurements were conducted on films of polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) and PS-b-poly(methyl methacrylate) (PS-b-PMMA), where the thickness of the film was varied from half the periodicity (L0) of the BCP to 5.5 L0. The results of this measurement on the PS-b-P2VP films show a significant expansion of the interface width immediately adjacent to the surface. This is likely caused by the strong adsorption of P2VP to the substrate, which constrains the mobility of the junction points, preventing them from reaching their equilibrium distribution and expanding the observed interface width. The interface width decays toward equilibrium moving away from the substrate, with the decay rate being a function of film thickness below a critical limit. The PMMA block appears to be more mobile, and the BCP interfaces near the substrate match their equilibrium value.
1 citations