Simulation of neutron dark-field data for grating-based interferometers.

Hierarchical structures and heterogeneous materials are found in many natural and engineered systems including additive manufacturing, alternative energy, biology and polymer science. Though the structure-function relationship is important for developing more advanced materials, structural characterization over broad length scales often requires multiple complementary measurements. Neutron far-field interferometry aims to enable multi-scale characterization by combining the best of neutron imaging with small-angle neutron scattering (SANS) via dark-field imaging.

Spin echo small-angle neutron scattering using superconducting magnetic Wollaston prisms.

We show the implementation of superconducting magnetic Wollaston prisms for spin echo small-angle neutron scattering. Two calibration methods for the spin echo length are presented: one utilizing spin echo modulated small-angle neutron scattering and the other based on the neutron refraction by quartz wedge crystals. Our experimental results with polystyrene nano-particle colloids showcase the system's efficacy in measuring both dilute and concentrated colloidal systems.

Data-driven simulations for training AI-based segmentation of neutron images.

Neutron interferometry uniquely combines neutron imaging and scattering methods to enable characterization of multiple length scales from 1 nm to 10 µm. However, building, operating, and using such neutron imaging instruments poses constraints on the acquisition time and on the number of measured images per sample. Experiment time-constraints yield small quantities of measured images that are insufficient for automating image analyses using supervised artificial intelligence (AI) models.

Biodegradable zwitterionic poly(carboxybetaine) microgel for sustained delivery of antibodies with extended stability and preserved function.

Many recent innovative treatments are based on monoclonal antibodies (mAbs) and other protein therapies. Nevertheless, sustained subcutaneous, oral or pulmonary delivery of such therapeutics is limited by the poor stability, short half-life, and non-specific interactions between the antibody (Ab) and delivery vehicle. Protein stabilizers (osmolytes) such as carboxybetaine can prevent non-specific interactions within proteins.

Multiscale Microstructure, Composition, and Stability of Surfactant/Polymer Foams.

Inclusion of polymer additives is a known strategy to improve foam stability, but questions persist about the amount of polymer incorporated in the foam and the resulting structural changes that impact material performance. Here, we study these questions in sodium dodecyl sulfate (SDS)/hydroxypropyl methylcellulose (HPMC) foams using a combination of flow injection QTOF mass spectrometry and small-angle neutron scattering (SANS) measurements leveraging contrast matching. Mass spectrometry results demonstrate polymer incorporation and retention in the foam during drainage by measuring the HPMC-to-SDS ratio.

Capillary RheoSANS: measuring the rheology and nanostructure of complex fluids at high shear rates.

Complex fluids containing micelles, proteins, polymers and inorganic nanoparticles are often processed and used in high shear environments that can lead to structural changes at the nanoscale. Here, capillary rheometry is combined with small-angle neutron scattering (SANS) to simultaneously measure the viscosity and nanostructure of model complex fluids at industrially-relevant high shear rates. Capillary RheoSANS (CRSANS) uses pressure-driven flow through a long, flexible, silica capillary to generate wall shear rates up to 10 s and measure pressure drops up to 500 bar.

Correlating inter-particle forces and particle shape to shear-induced aggregation/fragmentation and rheology for dilute anisotropic particle suspensions: A complementary study via capillary rheometry and in-situ small and ultra-small angle X-ray scattering.

Hypothesis: Understanding the stability and rheological behavior of suspensions composed of anisotropic particles is challenging due to the complex interplay of hydrodynamic and colloidal forces. We propose that orientationally-dependent interactions resulting from the anisotropic nature of non-spherical sub-units strongly influences shear-induced particle aggregation/fragmentation and suspension rheological behavior.

Experiments: Wide-, small-, and ultra-small-angle X-ray scattering experiments were used to simultaneously monitor changes in size and fractal dimensions of boehmite aggregates from 6 to 10,000 Å as the sample was recirculated through an in-situ capillary rheometer.

Color, structure, and rheology of a diblock bottlebrush copolymer solution.

A structure-property-process relation is established for a diblock bottlebrush copolymer solution, through a combination of rheo-neutron scattering, imaging, and rheological measurements. Polylactic acid-b-polystyrene diblock bottlebrush copolymers were dispersed in toluene with a concentration of 175 mg ml, where they self-assembled into a lamellar phase. All measurements were carried out at 5 °C.

Strain shifts under stress-controlled oscillatory shearing in theoretical, experimental, and structural perspectives: Application to probing zero-shear viscosity.

Rheological measurements in which the applied stress or strain is oscillated are widely used to interrogate viscoelastic properties due to the independent control over the time scale and length scale afforded by changes in amplitude and frequency. Taking a nontraditional approach, we treat stress-controlled oscillatory tests as creep tests with transiently varying stress and apply an analysis typically used for steady creep and recovery experiments. Defining zero strain as the state prior to external shearing, it is shown that strain responses to small-amplitude oscillatory stressing are naturally shifted from the starting point by an amount proportional to the phase of the applied stress.

Structure and Dynamics of Spherical and Rodlike Alkyl Ethoxylate Surfactant Micelles Investigated Using NMR Relaxation and Atomistic Molecular Dynamics Simulations.

Predicting and controlling the properties of amphiphile aggregate mixtures require understanding the arrangements and dynamics of the constituent molecules. To explore these topics, we study molecular arrangements and dynamics in alkyl ethoxylate nonionic surfactant micelles by combining NMR relaxation measurements with large-scale atomistic molecular dynamics simulations. We calculate parameters that determine relaxation rates directly from simulated trajectories, without introducing specific functional forms to describe the dynamics.

Poiseuille and extensional flow small-angle scattering for developing structure-rheology relationships in soft matter systems.

As the rheoscattering community has grown, so has the breadth of experiments both in terms of materials systems, and also in terms of flow types and analysis approaches. In this review, we seek to highlight important recent developments in rheoscattering that go beyond simple shear measurements. In particular, this review will focus on Poiseuille flow and extensional flow small-angle scattering and results from recent experiments that lead to the development of structure-function relationships in a wide variety of soft materials.

Structure-Property Relationships via Recovery Rheology in Viscoelastic Materials.

The recoverable strain is shown to correlate to the temporal evolution of microstructure via time-resolved small-angle neutron scattering and dynamic shear rheology. Investigating two distinct polymeric materials of wormlike micelles and fibrin network, we demonstrate that, in addition to the nonlinear structure-property relationships, the shear and normal stress evolution is dictated by the recoverable strain. A distinct sequence of physical processes under large amplitude oscillatory shear (LAOS) is identified that clearly contains information regarding both the steady-state flow curve and the linear-regime frequency sweep, contrary to most interpretations that LAOS responses are either distinct from or somehow intermediate between the two cases.

New insights into the flow and microstructural relaxation behavior of biphasic cellulose nanocrystal dispersions from RheoSANS.

Cellulose nanocrystals (CNC) have been studied as nanostructured building blocks for functional materials and function as a model nanomaterial mesogen for cholesteric (chiral nematic) liquid crystalline phases. In this study, both rheology and small angle neutron scattering (RheoSANS) were used to measure changes in flow-oriented order parameter and viscosity as a function of shear rate for isotropic, biphasic, liquid crystalline, and gel dispersions of CNC in deuterium oxide (DO). In contrast to plots of viscosity versus shear rate, the order parameter trends showed three distinct rheological regions over a range of concentrations.

Acid-induced assembly of a reconstituted silk protein system.

Silk cocoons are reconstituted into an aqueous suspension, and protein stability is investigated by comparing the protein's response to hydrochloric acid and sodium chloride. Aggregation occurs for systems mixed with hydrochloric acid, while sodium chloride over the same range of concentrations does not cause aggregation. We measure the structures present on the protein and aggregate length scales in these solutions using both optical and small-angle neutron scattering, while mass spectrometry techniques shed light on a possible mechanism for aggregate formation.

Peptide valency plays an important role in the activity of a synthetic fibrin-crosslinking polymer.

Therapeutic polymers have the potential to improve the standard of care for hemorrhage, or uncontrolled bleeding, as synthetic hemostats. PolySTAT, a fibrin-crosslinking peptide-polymer conjugate, has the capacity to rescue fibrin clot formation and improve survival in a model of acute traumatic bleeding. PolySTAT consists of a synthetic polymer backbone to which targeting fibrin-binding peptides are linked.

Quantifying "Softness" of Organic Coatings on Gold Nanoparticles Using Correlated Small-Angle X-ray and Neutron Scattering.

Small-angle X-ray and neutron scattering provide powerful tools to selectively characterize the inorganic and organic components of hybrid nanomaterials. Using hydrophobic gold nanoparticles coated with several commercial and dendritic thiols, the size of the organic layer on the gold particles is shown to increase from 1.2 to 4.

Fibrin clot structure and mechanics associated with specific oxidation of methionine residues in fibrinogen.

Using a combination of structural and mechanical characterization, we examine the effect of fibrinogen oxidation on the formation of fibrin clots. We find that treatment with hypochlorous acid preferentially oxidizes specific methionine residues on the α, β, and γ chains of fibrinogen. Oxidation is associated with the formation of a dense network of thin fibers after activation by thrombin.