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The use of block copolymers to compatibilize immiscible plastics is an important strategy for upcycling municipal plastic wastes. Multiblock copolymers (MBCPs) have been proven to be more effective compatibilizers than di- and tri-block copolymers. Herein, we probe the interface structure of an effective multiblock copolymer compatibilizer and compare that with an ineffective triblock copolymer (TBCP). The interface activity of the compatibilizers is understood through a combination of small-angle neutron and x-ray scatterings (SANS and SAXS), by using deuterated homopolymer matrix and protonated compatibilizers. SANS analysis suggests that the MBCP forms a thicker interface layer (7-9 nm) than the TBCP (0-4 nm). In addition, SANS data seems to point to a stronger tendency for the MBCP to locate at the interface. Both factors contribute to its effectiveness at compatibilizing immiscible homopolymers. [ABSTRACT FROM AUTHOR]

The microstructure of wormlike micelles (WLM) directly affects the rheological properties of their solutions. Investigating the structure–property relationships of WLM has long been a popular topic for researchers who have developed theoretical and empirical models to describe their viscoelastic behavior. All these models rely on a collection of characteristic "length" parameters that are often difficult to estimate using relatively simple rheological tests. In particular, the micelle stiffness, as described by the persistence length, can be difficult to measure experimentally, while being very impactful on the bulk rheology of WLM solutions. Here, an array of inorganic salts (NaCl, LiCl, MgCl2, NaBr, NaI, and Na2SO4) have been used to induce wormlike micelle formation in an aqueous solution of the surfactant sodium lauryl ether sulfate. Ion dissociation/association with the surfactant head groups and the hydrogen bond network of the water alters the effective stiffness of the micelles, allowing for an estimation of the stiffness using three different methods: (1) small angle neutron scattering (SANS) measurements, (2) oscillatory rheological measurements, and (3) steady rheological measurements with a thermodynamic packing parameter model. Each of these methods are then compared and shown to be consistent with each other for the micelle solutions tested. The consistency of the results across all the measurements suggests that the approach used in this study, which estimates micelle parameters using steady shear rheology and a thermodynamic model, could provide a simpler and more accessible method for estimating micelle parameters in a wide range of surfactant systems. [ABSTRACT FROM AUTHOR]

Despite being the major cause of safety and performance issues in lithium metal batteries, experimental difficulties in quantifying directly the morphology of lithium deposited at electrode surfaces have meant that the mechanism of metallic lithium growth within batteries remains elusive. This study demonstrates that quantitative detail about the morphology of metallic lithium within batteries can be derived non‐destructively and directly using in situ ultra‐small and small‐angle neutron scattering. This information is obtained over a large electrode area in cells where lithium deposition processes are typical of real‐world applications. Complex variations of surface area and interfacial distances 1–10 µm and 100–300 nm are revealed in size that are influenced by current density and cell cycling history, providing valuable insight into the growth of metallic lithium features detrimental to battery performance. Such quantitative insight into the process of lithium growth is required for the development of safer high‐performance lithium metal batteries. [ABSTRACT FROM AUTHOR]

Small‐Angle Scattering (SAS) techniques are essential tools for the characterization of catalysts before, during and after catalytic reactions. Either based on X‐Rays (SAXS) or neutrons (SANS), they provide unique structural information that helps to understand catalytic processes at the nanoscale level, allowing a rational improvement of the catalysts design. In this review, we present the key aspects involved in the use of these techniques in the catalysis field. Firstly, we introduce some of the fundamentals of the techniques and describe their main features and their impact in the catalyst design. Then, we analyze key examples of the use of SAS to study catalysts' structure through ex situ analysis, focusing on examples involving different porous materials and metallic nanoparticles. Afterwards, we discuss in situ and operando approaches for studying catalytical processes monitored using SAS. Finally, we present perspectives and challenges for the future use of SAS in the catalysis field. [ABSTRACT FROM AUTHOR]

X‐ray diffraction and small‐angle neutron scattering were used to identify the naturally occurring hormone auxin in Madeira vine. Two kinds of auxins belonging to indole‐3‐acetic acid (IAA, C10H9NO2) and 4‐chloroindole‐3‐acetic acid (4‐Cl‐IAA, C10H8ClNO2) have been found. The appearance of well‐defined x‐ray diffraction peaks from the IAA as well as from the 4‐Cl‐IAA structures shows that the IAA and 4‐Cl‐IAA molecules that are produced at the shoot apex crystallize into periodic arrangements, rather than stay in molecular forms, upon transport downward through in stem. Small angle neutron scattering spectra reveal a progressive increase in the length of crystallized IAA and 4‐Cl‐IAA on transported downward from the shoot apex to the stem, reaching 59 nm in length in the area 8–9 cm below the shoot apex. A portion of IAA loses their carboxyl group COOH becoming inactive in stimulating cell growth, which slows down the growth in an aged stem. [ABSTRACT FROM AUTHOR]

This study describes thermo‐rheological properties of branched copolymer surfactants (BCSs) stabilizing oil‐in‐water emulsions to generate materials exhibiting temperature‐dependent gelation with the ability to solubilize a broad range of molecules. Four poly(N‐isopropylacrylamide‐ran‐poly(ethylene glycol) methacrylate) (poly(NIPAM‐ran‐PEGMA)) BCSs with varying molecular weight (Mn), 4.7; 7.0; 7.8 and 9.0 kg mol−1, are investigated via oscillatory shear rheology, small angle neutron scattering (SANS), and neutron reflectivity (NR). Rheological thermoscans show that emulsions stabilized by the BCS with the lowest Mn (4.7 kg mol−1) are thermo‐thinning, while with the other BCSs the emulsions display a thermo‐thickening behavior. Emulsions stabilized with the BCS with Mn = 7.8 kg mol−1 form gels within a precise temperature window depending on BCS concentration. Small angle neutron scattering data analysis suggests that the BCS is present in two forms in equilibrium, small aggregates dispersed in the bulk water and an adsorbed polymeric layer at the oil/water interface. Changes in dimensions of these structures with temperature correlate with the macroscopic thermo‐thinning/thermo‐thickening behavior observed. Neutron reflectivity is conducted at the oil/water interface to allow further elucidation of BCS behavior in these systems. [ABSTRACT FROM AUTHOR]

Designing artificial protocells to sequester the biomolecules within its compartments is a challenging task and can be achieved through the use of surfactant‐based coacervates. Surfactant structures could be tailored to achieve the highest sequestration through coacervate droplets, irrespective of the polarity, charge and type of the analytes. Herein, we designed a morpholinium‐based ester‐functionalized ionic‐liquid‐based surfactant (ILBS) with a higher surface activity than its analogous conventional surfactant to form complex catanionic coacervates over the broad range of sodium salicylate (NaSal) concentrations. The spherically shaped micellar aggregates of the investigated ILBS are transformed into cylindrical shapes and again in the spherically shaped micellar aggregates depending on the NaSal concentration, which forms the coacervate droplets. The complex catanionic coacervates have been studied for their stability in the presence of mono and divalent cations, pH, temperature, viscosity and with respect to time. The microfluidic channel of 100 μm internal diameter was designed to obtain coacervate droplets with a maximum size of 100 μm. The coacervates were designed based on the NaSal concentration; cationic, neutral and anionic to exhibit selective and non‐selective encapsulation of the model charged dyes. We speculate that the strategically designed coacervate droplets could mimic membrane‐free protocells, which are applicable in multiple biomimetic operations. [ABSTRACT FROM AUTHOR]

Abstract: Two amphiphilic random copolymers, PEGMAx‐co‐FAy (x = 90 and 70 mol%), are synthesized by ATRP and their solutions are investigated as a function of solvent, concentration, and temperature by DLS and SANS analyses. Both copolymers self‐assemble in nanostructures by single‐chain folding in water solutions over a wide range of temperatures. The values of the DLS hydrodynamic radius and the SANS radius of gyration are found to be ≈4 nm and ≈3.4–3.7 nm, respectively. Moreover, SANS shows the self‐folded nanoassemblies to be prolated spheroids with a ratio of polar/equatorial axes of ≈5:1 for PEGMA90‐co‐FA10 and ≈2:1 for PEGMA70‐co‐FA30. On heating above a critical temperature Tc, multichain microassemblies are formed that revert back to nanoassemblies on cooling below Tc. This temperature‐responsive transition is fully and sharply reversible. [ABSTRACT FROM AUTHOR]

The most abundant cartilage proteoglycan is aggrecan, a bottlebrush shaped molecule that possesses over 100 glycosaminoglycan (chondroitin sulfate and keratan sulfate) chains. The side-chains are linear sulfated polysaccharides that are negatively charged under physiological conditions. Aggrecan interacts with hyaluronic acid (HA) to form large aggregates. Osmotic pressure measurements and rheological measurements are used to study the static and dynamic behavior of aggrecan assemblies at the macroscopic length scales. The microscopic properties of aggrecan solutions are determined by small angle neutron scattering, and static and dynamic light scattering (SLS and DLS). In dilute solutions aggrecan forms microgels with a diffuse boundary, composed of loosely connected clusters. The osmotic pressure of the aggrecan-HA system decreases with increasing HA content. DLS yields a relaxation rate that varies as q3, arising from internal modes in the microgel. The relaxation rate in the solutions of the aggrecan-HA complex is slightly greater than in the pure aggrecan solution. [ABSTRACT FROM AUTHOR]

ABSTRACT The purpose of this study is to identify the relationship between the electrical and structural characteristics of multiwalled carbon nanotubes dispersed into the polymer matrix of a resin. In a first step, the composites were characterized by small-angle neutron scattering, which provide information about the bulk dispersion of nanotubes in the matrix and form three-dimensional networks with a surface fractal behavior. In the second step, a dielectric and electrical study was carried out in the frequency range between 1 Hz and 10 MHz at room temperature. We have found that the electric and dielectric behavior of these composites can be described by Jonscher's universal dielectric response. We show that the critical exponents describing the concentration dependence of the conductivity and the dielectric constant, obtained in the vicinity of the percolation threshold, are in good agreement with the theoretical values. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44514. [ABSTRACT FROM AUTHOR]

Aggrecan is a charged biopolymer whose complexes with hyaluronic acid provide the compressive resistance of cartilage. In cartilage extracellular matrix aggrecan-hyaluronic acid complexes are enmeshed within a network of collagen fibrils. Osmotic pressure measurements and small angle neutron scattering (SANS) measurements are reported on solutions of aggrecan and aggrecan-hyaluronic acid complexes. These techniques probe the length scales relevant to the biological functions of cartilage. Osmotic pressure measurements indicate that dissolved aggrecan monomers form microgel-like assemblies. The osmotic pressure of aggrecan-hyaluronic acid complexes decreases with decreasing the ratio of aggrecan to hyaluronic acid. SANS reveals that there is no significant interpenetration between the neighboring aggrecan molecules. Both osmotic pressure measurements and SANS indicate weak interactions between the aggrecan bottlebrushes and collagen fibers. [ABSTRACT FROM AUTHOR]

The solution properties of the multiresponsive polymer P1 (poly(2-((3-(1-(2-(dimethylamino)ethyl)-1H-1,2,3-triazol-4-yl)propanoyl)oxy)ethyl methacrylate) are studied by small angle neutron scattering (SANS) and dynamic light scattering (DLS). The P1 solution exhibits a phase transition above certain temperatures and cloud points following dissolution through the incubation at room temperature. SANS and DLS studies show that P1 forms clusters via hydrophobic interactions, which are weakened by continued incubation. The temperature dependent cluster formation is explained by hydrophobic adsorption and shrinking behavior as a function of hydrodynamic radius, correlation lengths, and Porod exponents. The weak clustering and solution property are discussed on the basis of Flory theory. Taken together, the results here indicate that time-dependent dissolution of P1 leads to a weakly hydrophobic structure. [ABSTRACT FROM AUTHOR]

The effect of temperature on self-assembly of a novel type of amphiphilic ionic copolymers comprising a hydrophilic poly(acrylic acid) PAA block and an amphiphilic poly(acrylic acid)- grad-poly(styrene) PAA- grad-PS copolymer block has been studied by Small Angle Neutron and Dynamic Light Scattering (SANS, DLS). The polymers have been synthesized using direct Nitroxide-Mediated Polymerization (NMP) as described elsewhere and proved to be capable of formation of the equilibrium (dynamic) micelles responsive to variations in pH and ionic strength of the solution. We have demonstrated that an increase in temperature from 20 to 80 °C has almost no influence if the assembly occurs at pH∼6 in a wide range of salt concentration. Under these conditions stable micelle aggregates are formed. At pH∼6.9 virtually no aggregation occurs at any temperature in salt-free solution, whereas at 1 M salt concentration we observed an appearance of the correlation peak in the scattering curves and an increase in hydrodynamic radius in dilute solutions evidencing self-association of polymer chains. The magnitude of the correlation peak increases upon an increase in temperature. This behaviour may be attributed to the combined effect of temperature on the ionization constant and on the strength of hydrophobic interactions. [ABSTRACT FROM AUTHOR]

Structural biology provides essential information for elucidating molecular mechanisms that underlie biological function. Advances in hardware, sample preparation, experimental methods, and computational approaches now enable structural analysis of protein complexes with increasing complexity that more closely represent biologically entities in the cellular environment. Integrated multidisciplinary approaches are required to overcome limitations of individual methods and take advantage of complementary aspects provided by different structural biology techniques. Although X-ray crystallography remains the method of choice for structural analysis of large complexes, crystallization of flexible systems is often difficult and does typically not provide insights into conformational dynamics present in solution. Nuclear magnetic resonance spectroscopy (NMR) is well-suited to study dynamics at picosecond to second time scales, and to map binding interfaces even of large systems at residue resolution but suffers from poor sensitivity with increasing molecular weight. Small angle scattering (SAS) methods provide low resolution information in solution and can characterize dynamics and conformational equilibria complementary to crystallography and NMR. The combination of NMR, crystallography, and SAS is, thus, very useful for analysis of the structure and conformational dynamics of (large) protein complexes in solution. In high molecular weight systems, where NMR data are often sparse, SAS provides additional structural information and can differentiate between NMR-derived models. Scattering data can also validate the solution conformation of a crystal structure and indicate the presence of conformational equilibria. Here, we review current state-of-the-art approaches for combining NMR, crystallography, and SAS data to characterize protein complexes in solution. [ABSTRACT FROM AUTHOR]

Highlights: [•] Atomic structure models for RecA::RecX::ssDNA and RecX::ssDNA complexes are proposed. [•] RecX binds to RecA presynaptic filament in solution at the molar ratio close to 1:4. [•] RecX likely interacts with presynaptic complex DNA and intermonomer interface of RecA. [•] RecX protein can form sandwich-like filaments on ssDNA via Coulomb interactions. [Copyright &y& Elsevier]

Systematic investigations using small angle neutron scattering (SANS) were made to reveal the effect of calcium ions on the structure of DNA gels and solutions in near-physiological salt solutions. To describe the neutron scattering response two characteristic distances are required. The shorter length scale, R (≈10 Å), was found to be governed by the geometry of the DNA chain and is close to the cross-sectional radius of the double helix. The longer length scale L corresponds to the mesh size of the network of overlapping polymer chains. L decreases with increasing DNA concentration as L ∝ c DNA−0.73. With increasing CaCl2 concentration both L and the scattering intensity increase. The increase in the scattering intensity reflects the reduction of the osmotic modulus as the calcium ion concentration increases. The values of the osmotic modulus derived from osmotic swelling pressure measurements are in reasonable agreement with those obtained from SANS. [ABSTRACT FROM AUTHOR]

Abstract: Arrangement of chromatin in intact chicken erythrocyte nuclei was investigated by small angle neutron scattering. The scattering spectra have revealed that on the scales between 15nm and 1.5μm the interior of the nucleus exhibited properties of a mass fractal. The fractal dimension of the protein component of cell nucleus held constant at approximately 2.5, while the DNA organization was biphasic, with the fractal dimension slightly higher than 2 on the scales smaller than 300nm and approaching 3 on the larger scales. [Copyright &y& Elsevier]

We report osmotic swelling pressure and small angle neutron scattering (SANS) measurements made on DNA gels prepared in 40 mM NaCl solution. Two series of gels were made: in the first the crosslinks were introduced in the absence of CaCl2, while in the second the DNA was crosslinked in solutions containing 40 mM NaCl with different amounts of CaCl2. The swelling pressure of the gels was determined as a function of the DNA concentration at constant salt concentrations. It was found that gels prepared in the presence of CaCl2 exhibited significantly lower swelling pressure than the corresponding gels made in CaCl2 free solutions. SANS revealed the presence of large clusters (>1000 Å) dominating the scattering signal at low values of q. In the intermediate q‐range the SANS intensity varied as q−1, in agreement with the linear character of the DNA chains. From the SANS response in the high q region the thermodynamic component of the concentration fluctuations, Idyn(0), was estimated. It was shown that Idyn(0) determined from SANS was in good agreement with the intensity calculated from osmotic swelling pressure measurements. [ABSTRACT FROM AUTHOR]

The phase‐separated network structure of amphiphilic copolymer gels composed of poly(dimethyl siloxane) (PDMS) and poly(N,N‐dimethyl acrylamide) (PDMAA) in water and a water/methanol mixture is investigated by small angle X‐ray (SAXS) and small angle neutron scatterings (SANS). The copolymerized gel of PDMS‐co‐PDMAA exhibits bicontinuous phase‐separated domains (hydrophilic and hydrophobic) with a periodicity at the nanometer scale, and the PDMS hydrophobic domain forms a cylinder‐like core. The hydrophilic region is confirmed to be selectively swollen by water and methanol. Deuterated water and deuterated methanol are used for the SAXS and SANS measurements. The electron density and scattering length density (SLD) of the hydrophilic region vary according to the mixture ratio and adsorption amount of the solvents. The SAXS profiles (curve and scattering intensity) significantly change with the ratio D2O/methanol‐d4. On the other hand, the SANS profiles do not change significantly. The deuterated solvents cannot be distributed into the PDMS domain (core). The solvents and PDMAA hydrophilic form matrix. In these situations, as for SANS, the SLD difference between the PDMS and matrix remains almost constant. As for SAXS, in contrast to SANS, the electron density difference between the PDMS and hydrophilic domain varies with the ratio of water to methanol. The SAXS and SANS profiles can be simulated using a core‐shell cylindrical model. We found that an interfacial thin region exists between the hydrophobic PDMS and hydrophilic PDMAA/solvents. This interfacial region is determined to be composed of a solvent–poor PDMAA. [ABSTRACT FROM AUTHOR]