TY - JOUR A1 - Henning, L. M. A1 - Müller, J. T. A1 - Smales, Glen Jacob A1 - Pauw, Brian Richard A1 - Schmidt, J. A1 - Bekheet, M. F. A1 - Gurlo, A. A1 - Simon, U. T1 - Hierarchically porous and mechanically stable monoliths from ordered mesoporous silica and their water filtration potential N2 - Mechanically stable structures with interconnected hierarchical porosity combine the benefits of both small and large pores, such as high surface area, pore volume, and good mass transport capabilities. Hence, lightweight micro-/meso-/macroporous monoliths are prepared from ordered mesoporous silica COK-12 by means of spark plasma sintering (SPS, S-sintering) and compared to conventionally (C-) sintered monoliths. A multi-scale model is developed to fit the small angle X-ray scattering data and obtain information on the hexagonal lattice parameters, pore sizes from the macro to the micro range, as well as the dimensions of the silica population. For both sintering techniques, the overall mesoporosity, hexagonal pore ordering, and amorphous character are preserved. The monoliths' porosity (77–49%), mesopore size (6.2–5.2 nm), pore volume (0.50–0.22 g cm-3 ), and specific surface area (451–180 m2 g-1) decrease with increasing processing temperature and pressure. While the difference in porosity is enhanced, the structural parameters between the C-and S-sintered monoliths are largely converging at 900 C, except for the mesopore size and lattice parameter, whose dimensions are more extensively preserved in the S-sintered monoliths, however, coming along with larger deviations from the theoretical lattice. Their higher mechanical properties (biaxial strength up to 49 MPa, 724 MPa HV 9.807 N) at comparable porosities and ability to withstand ultrasonic treatment and dead-end filtration up to 7 bar allow S-sintered monoliths to reach a high permeance (2634 L m-2 h-1 bar-1), permeability (1.25 x 10^-14 m2), and ability to reduce the chemical oxygen demand by 90% during filtration of a surfactant-stabilized oil in water emulsion, while indicating reasonable resistance towards fouling. KW - SAXS KW - Hierarchically porous KW - Silica KW - Water filtration PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-555928 DO - https://doi.org/10.1039/D2NA00368F SN - 2516-0230 SP - 1 EP - 17 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-55592 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hoevelmann, J. A1 - Stawski, T. M. A1 - Besselink, R. A1 - Freeman, H. M. A1 - Dietmann, K. M. A1 - Mayanna, S. A1 - Pauw, Brian Richard A1 - Benning, L. G. T1 - A template-free and low temperature method for the synthesis of mesoporous magnesium phosphate with uniform pore structure and high surface area N2 - Mesoporous phosphates are a group of nanostructured materials with promising applications, particularly in biomedicine and catalysis. However, their controlled synthesis via conventional template-based routes presents a number of challenges and limitations. Here, we show how to synthesize a mesoporous Magnesium phosphate with a high surface area and a well-defined pore structure through thermal decomposition of a crystalline struvite (MgNH4PO4·6H2O) precursor. In a first step, struvite crystals with various morphologies and sizes, ranging from a few micrometers to several millimeters, had been synthesized from supersaturated aqueous solutions (saturation index (SI) between 0.5 and 4) at ambient pressure and temperature conditions. Afterwards, the crystals were thermally treated at 70–250 °C leading to the release of structurally bound water (H2O) and ammonia (NH3). By combining thermogravimetric analyses (TGA), scanning and transmission electron microscopy (SEM, TEM), N2 sorption analyses and small- and wide-angle X-ray scattering (SAXS/WAXS) we show that this decomposition process results in a pseudomorphic transformation of the original struvite into an amorphous Mg-phosphate. Of particular importance is the fact that the final material is characterized by a very uniform mesoporous structure with 2–5 nm wide pore channels, a large specific surface area of up to 300 m2 g−1 and a total pore volume of up to 0.28 cm3 g−1. Our struvite decomposition method is well controllable and reproducible and can be easily extended to the synthesis of other mesoporous phosphates. In addition, the so produced mesoporous material is a prime candidate for use in biomedical applications considering that Magnesium phosphate is a widely used, non-toxic substance that has already shown excellent biocompatibility and biodegradability. KW - Struvite KW - SAXS KW - Scattering KW - Nanoporous KW - Geology PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-477130 DO - https://doi.org/10.1039/c8nr09205b VL - 11 IS - 14 SP - 6939 EP - 6951 PB - Royal Society of Chemistry AN - OPUS4-47713 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 - Huang, J. A1 - Tarábek, J. A1 - Kulkarni, R. A1 - Wang, Cui A1 - Dračínský, M. A1 - Smales, Glen Jacob A1 - Pauw, Brian Richard A1 - Resch-Genger, Ute A1 - Bojdys, M. J. T1 - A π-conjugated, covalent phosphinine framework N2 - Structural modularity of polymer frameworks is a key advantage of covalent organic polymers, however, only C, N, O, Si and S have found their way into their building blocks so far. Here, we expand the toolbox available to polymer and materials chemists by one additional nonmetal, phosphorus. Starting with a building block that contains a λ⁵‐phosphinine (C₅P) moiety, we evaluate a number of polymerisation protocols, finally obtaining a π‐conjugated, covalent phosphinine‐based framework (CPF‐1) via Suzuki‐Miyaura coupling. CPF‐1 is a weakly porous polymer glass (72.4 m2 g‐1 N2 BET at 77 K) with green fluorescence (λmax 546 nm) and extremely high thermal stability. The polymer catalyzes hydrogen evolution from water under UV and visible light irradiation without the need for additional co‐catalyst at a rate of 33.3 μmol h‐¹ g‐¹. Our results demonstrate for the first time the incorporation of the phosphinine motif into a complex polymer framework. Phosphinine‐based frameworks show promising electronic and optical properties that might spark future interest in their applications in light‐emitting devices and heterogeneous catalysis. KW - Phosphinine KW - Fully aromatic frameworks KW - Suzuki-Miyaura coupling KW - Polymers KW - Fluorescence KW - Small-angle scattering PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-485330 DO - https://doi.org/10.1002/chem.201900281 SP - 2 EP - 10 PB - Wiley VCH-Verlag CY - Weinheim AN - OPUS4-48533 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hunter, R. D. A1 - Hayward, E. C. A1 - Smales, Glen Jacob A1 - Pauw, Brian Richard A1 - Kulak, A. A1 - Guan, S. A1 - Schnepp, Z. T1 - The effect of nitrogen on the synthesis of porous carbons by iron-catalyzed graphitization N2 - This paper reports a systematic study into the effect of nitrogen on iron-catalyzed graphitization of biomass. Chitin, chitosan, N-acetylglucosamine, gelatin and glycine were selected to represent nitrogen-rich saccharides and amino-acid/polypeptide biomass precursors. The materials were pyrolyzed with an iron catalyst to produce carbons with a wide range of chemical and structural features such as mesoporosity and nitrogen-doping. Many authors have reported the synthesis of nitrogen-doped carbons by pyrolysis and these have diverse applications. However, this is the first systematic study of how nitrogen affects pyrolysis of biomass and importantly the catalytic graphitization step. Our data demonstrates that nitrogen inhibits graphitization but that some nitrogen survives the catalytic graphitization process to become incorporated into various chemical environments in the carbon product. KW - Graphitization KW - Nanoparticles KW - Nanocomposite KW - Porous carbon KW - Nitrogen KW - Scattering PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-575351 DO - https://doi.org/10.1039/d3ma00039g VL - 4 SP - 2070 EP - 2077 PB - Royal Society of Chemistry AN - OPUS4-57535 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 - CONF A1 - Pauw, Brian Richard T1 - Coping with the EU Nano-definition: abilities and limitations of particle sizing with SAXS N2 - Excelling in brevity but lacking in applicability, the 2011 EU nanomaterial definition has become a source of anguish for scientists and industry alike. Repeated pleas and discussions with our own envoy have demonstrated the strength of their resolve: this definition is unlikely to change. Manufacturers of many materials (cosmetics, pigments, foodstuffs, etc.) will have to characterise and label all their products accordingly, a task still impossible for lack of a clear metrological approach towards this goal. Therefore, the onus has fallen on the scientists to come up with a practicable measurement technique allowing inexpensive classification covering large swathes of the material landscape. Small-angle X-ray Scattering (SAXS) probes the size range in question, and can - with due care - deliver a bulk-averaged volume-weighted size distribution. Like any other real-world measurement method, however, it is not (and can never be) a universal solution. This presentation will clarify the SAXS technique, provide several application examples for nanomaterial characterisation, and will detail the limitations and pitfalls that accompany its abilities. At the end of this presentation, you will have the information to judge whether the technique is amenable to your materials or not. T2 - 2016 TechConnect World Innovation Conference CY - National Harbor, MD, USA DA - 23.05.2016 KW - SAXS KW - presentation KW - EU KW - Nanomaterial PY - 2016 AN - OPUS4-36489 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pauw, Brian Richard T1 - The dark side of science N2 - This talk explores the various ways in which bad science can proliferate in the current academic environment, and what can be done to recognize and (maybe) correct it. T2 - Better with Scattering workshop 2020 CY - BAM, Berlin, Germany DA - 16.03.2020 KW - Scientific rigor KW - Academic fraud KW - Academic metrics PY - 2020 AN - OPUS4-51017 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pauw, Brian Richard T1 - McSAS for SAS analysis: Usage, Benefits and Potential Pitfalls N2 - This talk introduces McSAS, code for analysis of scattering patterns to extract particle size distributions. It highlights how it works, how it should be used, and when it may (not) be applied T2 - Better with Scattering workshop 2020 CY - BAM, Berlin, Germany DA - 16.03.2020 KW - Small angle scattering KW - Software KW - Analysis PY - 2020 AN - OPUS4-51019 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pauw, Brian Richard T1 - The Dark Side of Science N2 - An overview of the dark side of science: what it is, how it occurs, and what you can do to understand it and fight for the light side. T2 - First training event of the ITN-Project GW4SHM CY - Online meeting DA - 23.11.2020 KW - Scientific rigor KW - Scientific misconduct KW - Data manipulation KW - Image manipulation PY - 2020 AN - OPUS4-51830 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -