Shape2SAS -- a web application to simulate small-angle scattering data and pair distance distributions from user-defined shapes

Shape2SAS is a web application that allows researchers and students to build intuition and understanding of small-angle scattering. It is available at https://somo.chem.utk.edu/shape2sas. The user defines a model of arbitrary shape by combining geometrical subunits, and Shape2SAS then calculates and displays the scattering intensity, the pair distance distribution as well as a visualization of the user-defined shape. Simulated data with realistic noise are also generated. We demonstrate how Shape2SAS can calculate and display the different scattering patterns for various geometrical shapes, such as spheres and cylinders. We also demonstrate how the effect of structure factors can be visualized. Finally, we show how multi-contrast particles can readily be generated, and how the calculated scattering may be used to validate and visualize analytical models generated in analysis software for fitting small-angle scattering data

Bulk and surface morphologies of ABC miktoarm star terpolymers comprised of PDMS, PI and PMMA arms

DIM miktoarm star copolymers, composed of polydimethylsiloxane [D], poly(1,4-isoprene) [I], and poly(methyl methacrylate) [M], were synthesized using a newly developed linking methodology with 4-allyl-1,1-diphenylethylene as a linking agent. The equilibrium bulk morphologies of the DIM stars were found to range from [6.6.6] tiling patterns to alternating lamellar and alternating cylindrical morphologies, as determined experimentally by small-angle X-ray scattering and transmission electron microscopy and confirmed by dissipative particle dynamics and self-consistent field theory based arguments. The thin film morphologies, which differ from those found in the bulk, were identified by scanning electron microscopy, coupled with oxygen plasma etching. Square arrays of the PDMS nanodots and empty core cylinders were formed on silica after oxygen plasma removal of the poly(1,4-isoprene) and poly(methyl methacrylate) which generated nanostructured substrates decorated with these features readily observable

Kaleidoscopic tilings, networks and hierarchical structures in blends of 3-miktoarm star terpolymers

Dissipative particle dynamics simulations are used to explore blends of 3-miktoarm star terpolymers. The investigated system is a 50/50 blend of ABC and ABD stars, which is investigated as a function of composition and at different symmetric segregation levels. The study shows that in analogy to pure ABC star melts cylindrical tiling patters form, but now in four-coloured variants. Also, a large part of the phase diagram is dominated by multi-coloured network structures showing hierarchical features. Most prominently, a novel alternating gyroid network structure with a hyperbolic lamellar interface is predicted to form. Here, the two gyroidal nets are composed of respectively C and D components, with the minority A and B components forming the lamellar-like curved structure on the dividing interface between the two nets