TY - JOUR A1 - Szymoniak, Paulina A1 - Pauw, Brian Richard A1 - Qu, Xintong A1 - Schönhals, Andreas T1 - Competition of nanoparticle-induced mobilization and immobilization effects on segmental dynamics of an epoxy-based nanocomposite N2 - The complex effects of nanoparticles on a thermosetting material based on an anhydride cured DGEBA/Boehmite nanocomposite with different particle concentrations is considered. A combination of X-ray scattering, calorimetry, including fast scanning calorimetry as well as temperature modulated calorimetry and dielectric spectroscopy, was employed to study the structure, the vitrification kinetics and the molecular dynamics of the nanocomposites. For the first time in the literature for an epoxy-based composite a detailed analysis of the X-ray data was carried out. Moreover, the unfilled polymer was found to be intrinsically heterogeneous, showing regions with different crosslinking density, indicated by two separate dynamic glass transitions. The glass transition temperature decreases with increasing nanoparticle concentration, resulting from a change in the crosslinking density. Moreover, on the one hand, for nanocomposites the incorporation of nanofiller increased the number of mobile segments for low nanoparticle concentrations, due to the altered crosslinking density. On the other hand, for higher loading degrees the number of mobile segments decreased, resulting from the formation of an immobilized interphase (RAF). The simultaneous mobilization and immobilization of the segmental dynamics cannot be separated unambiguously. Taking the sample with highest number of mobile segments as reference state it was possible to estimate the amount of RAF. KW - Nanocomposite PY - 2020 DO - https://doi.org/10.1039/d0sm00744g SN - 1744-683X VL - 16 IS - 23 SP - 5406 EP - 5421 PB - Royal Chemical Society AN - OPUS4-50883 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Aratsu, K. A1 - Takeya, R. A1 - Pauw, Brian Richard A1 - Hollamby, M.J. A1 - Kitamoto, Y. A1 - Shimizu, N. A1 - Takagi, H. A1 - Haruki, R. A1 - Adachi, S. A1 - Yagai, S. T1 - Supramolecular copolymerization driven by integrative self-sorting of hydrogen-bonded rosettes N2 - Molecular recognition to preorganize noncovalently polymerizable supramolecular complexes is a characteristic process of natural supramolecular polymers, and such recognition processes allow for dynamic self-alteration, yielding complex polymer systems with extraordinarily high efficiency in their targeted function. We herein show an example of such molecular recognition-controlled kinetic assembly/disassembly processes within artificial supramolecular polymer systems using six-membered hydrogen-bonded supramolecular complexes (rosettes). Electron-rich and poor monomers are prepared that kinetically coassemble through a temperature-controlled protocol into amorphous coaggregates comprising a diverse mixture of rosettes. Over days, the electrostatic interaction between two monomers induces an integrative self-sorting of rosettes. While the electron-rich monomer inherently forms toroidal homopolymers, the additional electrostatic interaction that can also guide rosette association allows helicoidal growth of supramolecular copolymers that are comprised of an alternating array of two monomers. Upon heating, the helicoidal copolymers undergo a catastrophic transition into amorphous coaggregates via entropy-driven randomization of the monomers in the rosette. KW - Self-assembly KW - Coaggregation KW - Scattering KW - Simulation KW - AFM PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-506555 DO - https://doi.org/10.1038/s41467-020-15422-6 VL - 11 IS - 1 SP - Article number: 1623 PB - Springer Nature AN - OPUS4-50655 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ryan, T. M. A1 - Xun, Y. A1 - Cowieson, N. P. A1 - Mata, J. P. A1 - Jackson, A. A1 - Pauw, Brian Richard A1 - Smith, A. J. A1 - Kirby, N. A1 - McGillivray, D. T1 - Combined pressure and temperature denaturation of ribonuclease A produces alternate dentatured states N2 - Protein folding, unfolding and misfolding have become critically important to a range of health and industry applications. Increasing high temperature and high pressure are used to control and speed up reactions. A number of studies have indicated that these parameters can have a large effecton protein structure and function. Here we describe the additive effects of these parameters on the small angle scattering behaviour of ribonuclease A. We find that alternate unfolded structures can be obtained with combined high pressure and temperature treatment of the protein. KW - Protein unfolding KW - Small angle scattering KW - Ribonuclease A KW - High pressure PY - 2016 DO - https://doi.org/10.1016/j.bbrc.2016.03.135 SN - 0006-291X IS - 473 SP - 834 EP - 839 PB - Academic Press Inc Elsevier Science CY - San Diego, USA AN - OPUS4-36052 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szymoniak, Paulina A1 - Qu, Xintong A1 - Abbasi, M. A1 - Pauw, Brian Richard A1 - Henning, S. A1 - Li, Z. A1 - Wang, D.-Y. A1 - Schick, C. A1 - Saalwächter, K. A1 - Schönhals, Andreas T1 - Spatial inhomogeneity, Interfaces and Complex Vitrification Kinetics in a Network Forming Nanocomposite N2 - A detailed calorimetric study on an epoxy-based nanocomposite system was performed employing bisphenol A diglycidyl ether (DGEBA) cured with diethylenetriamine (DETA) as the polymer matrix and taurine-modified MgAL layered double hydroxide (T-LDH) as nanofiller. The -NH2 group of taurine can react with DGEBA improving the interaction of the polymer with the filler. The combined X-ray scattering, and electron microscopy data showed that the nanocomposite has a partially exfoliated morphology. Calorimetric studies were performed with conventional DSC, temperature modulated DSC (TMDSC) and fast scanning calorimetry (FSC) in the temperature modulated approach (TMFSC) to investigate the vitrification and molecular mobility in dependence of the filler concentration. First, TMDSC and NMR were used to estimate the amount of the rigid amorphous fraction which consists of immobilized polymer segments at the nanoparticle surface. It was found to be 40 wt% for the highest filler concentration, indicating that the interface dominates the overall macroscopic properties and behavior of the material to a great extent. Second, the relaxation rates of the α-relaxation obtained by TMDSC and TMFSC were compared with the thermal and dielectric relaxation rates measured by static FSC. The investigation revealed that the system shows two distinct α-relaxation processes. Furthermore, also two separate vitrification mechanisms were found for a bulk network-former without geometrical confinement as also confirmed by NMR. This was discussed in terms of the intrinsic spatial heterogeneity on a molecular scale, which becomes more pronounced with increasing nanofiller content. KW - Polymer based Nanocomposites PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-523199 DO - https://doi.org/10.1039/d0sm01992e SN - 1744-6848 VL - 17 IS - 10 SP - 2775 EP - 2790 PB - Royal Society of Chemistry AN - OPUS4-52319 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Deumer, J. A1 - Pauw, Brian Richard A1 - Marguet, S. A1 - Skroblin, D. A1 - Taché, O. A1 - Krumrey, M. A1 - Gollwitzer, C. T1 - Small-angle X-ray scattering: characterization of cubic Au nanoparticles using Debye’s scattering formula N2 - A versatile software package in the form of a Python extension, named CDEF (computing Debye’s scattering formula for extraordinary form factors), is proposed to calculate approximate scattering profiles of arbitrarily shaped nanoparticles for small-angle X-ray scattering (SAXS). CDEF generates a quasi-randomly distributed point cloud in the desired particle shape and then applies the open-source software DEBYER for efficient evaluation of Debye’s scattering formula to calculate the SAXS pattern (https://github.com/j-from-b/CDEF). If self-correlation of the scattering signal is not omitted, the quasi-random distribution provides faster convergence compared with a true-random distribution of the scatterers, especially at higher momentum transfer. The usage of the software is demonstrated for the evaluation of scattering data of Au nanocubes with rounded edges, which were measured at the four-crystal monochromator beamline of PTB at the synchrotron radiation facility BESSY II in Berlin. The implementation is fast enough to run on a single desktop computer and perform model fits within minutes. The accuracy of the method was analyzed by comparison with analytically known form factors and verified with another implementation, the SPONGE, based on a similar principle with fewer approximations. Additionally, the SPONGE coupled to McSAS3 allows one to retrieve information on the uncertainty of the size distribution using a Monte Carlo uncertainty estimation algorithm. KW - X-ray scattering KW - SAXS KW - Non-spherical nanoparticles KW - Nanoparticles KW - Nanomaterials KW - Debye scattering equation KW - Simulation KW - Data fitting PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-557652 DO - https://doi.org/10.1107/S160057672200499X VL - 55 IS - Pt 4 SP - 993 EP - 1001 PB - International Union of Crystallography CY - Chester, England AN - OPUS4-55765 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chambers, M. S. A1 - Hunter, R. D. A1 - Hollamby, M. J. A1 - Pauw, Brian Richard A1 - Smith, A. J. A1 - Snow, T. A1 - Danks, A. E. A1 - Schnepp, Z. T1 - In Situ and Ex Situ X‑ray Diffraction and Small-Angle X‑ray Scattering Investigations of the Sol−Gel Synthesis of Fe3N and Fe3C N2 - Iron nitride (Fe3N) and iron carbide (Fe3C) nanoparticles can be prepared via sol−gel synthesis. While sol−gel methods are simple, it can be difficult to control the crystalline composition, i.e., to achieve a Rietveld-pure product. In a previous in situ synchrotron study of the sol−gel synthesis of Fe3N/Fe3C, we showed that the reaction proceeds as follows: Fe3O4 → FeOx → Fe3N → Fe3C. There was considerable overlap between the different phases, but we were unable to ascertain whether this was due to the experimental setup (side-on heating of a quartz capillary which could lead to thermal gradients) or whether individual particle reactions proceed at different rates. In this paper, we use in situ wide- and small-angle X-ray scattering (wide-angle X-ray scattering (WAXS) and small-angle X-ray scattering (SAXS)) to demonstrate that the overlapping phases are indeed due to variable reaction rates. While the initial oxide nanoparticles have a small range of diameters, the size range expands considerably and very rapidly during the oxide−nitride transition. This has implications for the isolation of Rietveld-pure Fe3N, and in an extensive laboratory study, we were indeed unable to isolate phasepure Fe3N. However, we made the surprising discovery that Rietveld-pure Fe3C nanoparticles can be produced at 500 °C with a sufficient furnace dwell time. This is considerably lower than the previous reports of the sol−gel synthesis of Fe3C nanoparticles. KW - Small-angle X-ray Scattering KW - SAXS KW - Diffraction KW - XRD KW - Scattering KW - Sol-gel KW - Iron nitride KW - Nanoparticles KW - Iron carbide KW - Catalyst KW - In-situ KW - Ex-situ KW - Synthesis KW - Synchrotron PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-548226 DO - https://doi.org/10.1021/acs.inorgchem.1c03442 VL - 61 IS - 18 SP - 6742 EP - 6749 PB - ACS Publications CY - Washington AN - OPUS4-54822 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krauss, S. W. A1 - Eckardt, M. A1 - Will, J. A1 - Spiecker, E. A1 - Siegel, R. A1 - Dulle, M. A1 - Schweins, R. A1 - Pauw, Brian Richard A1 - Senker, J. A1 - Zobel, M. T1 - H-D-isotope effect of heavy water affecting ligand-mediated nanoparticle formation in SANS and NMR experiments N2 - An isotopic effect of normal (H2O) vs. heavy water (D2O) is well known to fundamentally affect structure and chemical properties of proteins, for instance. Here we correlate results from small angle X-ray and neutron scattering (SAXS, SANS) with high-resolution scanning transmission electron microscopy to track the evolution of CdS nanoparticle size and crystallinity from aqeuous solution in presence of the organic ligand ethylenediaminetetraacetate (EDTA) at room temperature in both H2O and D2O. We provide evidence via SANS experiments that exchanging H2O by D2O impacts nanoparticle formation by changing the equilibria and dynamics of EDTA clusters in solution as investigated by nuclear magnetic resonance. The colloidal stability of the CdS nanoparticles, covered by a layer of [Cd(EDTA)]2- complexes, is significantly reduced in D2O despite the strong stabilizing effect of EDTA in suspensions of normal water. Hence, conclusions about nanoparticle formation mechanisms from D2O solutions can bare limited transferability to reactions in normal water due to isotopic effects, which thus need to be discussed for contrast match experiments. KW - General Materials Science KW - Quantum dots KW - CdS KW - Deuterium KW - X-ray scattering KW - MOUSE PY - 2023 DO - https://doi.org/10.1039/D3NR02419A SN - 2040-3364 VL - 15 IS - 40 SP - 16413 EP - 16424 PB - Royal Society of Chemistry (RSC) AN - OPUS4-58294 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hollamby, M. J. A1 - Smith, C. F. A1 - Britton, M. M. A1 - Danks, A. E. A1 - Schnepp, Z. A1 - Grillo, I. A1 - Pauw, Brian Richard A1 - Kishimura, A. A1 - Nakanishi, T. T1 - The aggregation of an alkyl–C60 derivative as a function of concentration, temperature and solvent type N2 - Contrast-variation small-angle neutron scattering (CV-SANS), small-angle X-ray scattering (SAXS), nuclear magnetic resonance (NMR) measurements of diffusion and isothermal titration calorimetry (ITC) are used to gain insight into the aggregation of an alkyl–C60 derivative, molecule 1, in n-hexane, n-decane and toluene as a function of concentration and temperature. Results point to an associative mechanism of aggregation similar to other commonly associating molecules, including non-ionic surfactants or asphaltenes in non-aqueous solvents. Little aggregation is detected in toluene, but small micelle-like structures form in n-alkane solvents, which have a C60-rich core and alkyl-rich shell. The greatest aggregation extent is found in n-hexane, and at 0.1 M the micelles of 1 comprise around 6 molecules at 25 °C. These micelles become smaller when the concentration is lowered, or if the solvent is changed to n-decane. The solution structure is also affected by temperature, with a slightly larger aggregation extent at 10 °C than at 25 °C. At higher concentrations, for example in solutions of 1 above 0.3 M in n-decane, a bicontinuous network becomes apparent. Overall, these findings aid our understanding of the factors driving the assembly of alkyl–π-conjugated hydrophobic amphiphiles such as 1 in solution and thereby represent a step towards the ultimate goal of exploiting this phenomenon to form materials with well-defined order. KW - Complex Molecular Systems KW - Supramolecules KW - Scattering PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-442977 DO - https://doi.org/10.1039/C7CP06348B VL - 20 IS - 5 SP - 3773 EP - 3380 PB - RSC AN - OPUS4-44297 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hollamby, M. J. A1 - Aratsu, K. A1 - Pauw, Brian Richard A1 - Rogers, S. E. A1 - Smith, A. J. A1 - Yamauchi, M. A1 - Lin, X. A1 - Yagai, S. T1 - Simultaneous SAXS and SANS Analysis for the Detection of Toroidal Supramolecular Polymers Composed of Noncovalent Supermacrocycles in Solution N2 - Molecular self-assembly primarily occurs in solution. To better understand this process, techniques capable of probing the solvated state are consequently required. Smallangle scattering (SAS) has a proven ability to detect and characterize solutions, but it is rarely applied to more complex assembly shapes. Here, small-angle X-ray and neutron scattering are applied to observe toroidal assemblies in solution. Combined analysis confirms that the toroids have a core–shell structure, with a p-conjugated core and an alkyl shell into which solvent penetrates. The dimensions determined by SAS agree well with those obtained by (dried-state) atomic force microscopy. Increasing the number of naphthalene units in the molecular building block yields greater rigidity, as evidenced by a larger toroid and a reduction in solvent penetration into the shell. The detailed structural analysis demonstrates the applicability of SAS to monitor complex solution-based selfassembly. KW - Nanorings KW - Self-assembly KW - Small-angle scattering KW - Supramolecular chemistry KW - Toroids PY - 2016 DO - https://doi.org/10.1002/anie.201603370 SN - 1433-7851 SN - 1521-3773 IS - 128 SP - 10044 EP - 10047 PB - Wiley-VCH Verlag GmbH CY - Weinheim AN - OPUS4-37144 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kolmangadi, Mohamed A. A1 - Zhuoqing, L. A1 - Smales, Glen Jacob A1 - Pauw, Brian Richard A1 - Wuckert, E. A1 - Raab, A. A1 - Laschat, S. A1 - Huber, P. A1 - Schönhals, Andreas T1 - Confinement-suppressed phase transition and dynamic self-assembly of ionic superdiscs in ordered nanochannels: Implication for nanoscale applications N2 - Ionic Liquid Crystals are ionic liquids that exhibit liquid crystalline mesomorphism together with ionic conductivity. As known confined liquid crystal mesophases can show an anomalous dynamics and phase behavior. Investigations considering the factors controlling the macroscopic properties of ILCs in confinement are scare in the literature. This study reports the molecular mobility, and the phase transition behavior of a guanidinium based columnar ILC confined in the nanopores of self-ordered anodic aluminum oxide membranes of various pore diameters (25 – 180 nm) using Broadband Dielectric Spectroscopy (BDS), calorimetry and X-ray scattering. It is aimed to reveal in which way the pore size as well as the pore surface wettability (hydrophobic or hydrophilic) alters the molecular dynamics, and phase transition behavior for this system. These properties are crucial for applications. The DSC investigations reveal: (i) the phase transition temperature for the transition from the plastic crystalline to the crystalline-liquid state has non-monotonic dependence versus the inverse pore diameter and (ii) the transition from the liquid crystalline to the isotropic phase is suppressed for all nanoconfined samples. This transition suppressed in the thermal signal was evidenced by BDS and X-ray scattering. It is discussed as a continuous phase transition taking place in the pores instead of a discontinuous first order transition as observed for the bulk. BDS investigations show different relaxation processes for the bulk and the nanoconfined ILC. Molecular origins for various relaxation processes are discussed and suggested. It is further shown that the self-assembly of this ILC is dynamic in nature which might apply for other ILCs too. The obtained results will have implications for the nanoscale applications of ionic liquid crystals. KW - Ionic Liquid Crystals PY - 2023 DO - https://doi.org/10.1021/acsanm.3c02473 VL - 6 IS - 17 SP - 15673 EP - 15684 PB - ACS AN - OPUS4-58210 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -