TY - JOUR A1 - Wang, Z. A1 - Villa Santos, C. A1 - Legrand, A. A1 - Haase, F. A1 - Hara, Y. A1 - Kanamori, K. A1 - Aoyama, T. A1 - Urayama, K. A1 - Doherty, C. M. A1 - Smales, Glen Jacob A1 - Pauw, Brian Richard A1 - Colon, Y. J. A1 - Furukawa, S. T1 - Multiscale structural control of linked metal–organic polyhedra gel by aging-induced linkage-reorganization N2 - Assembly of permanently porous metal–organic polyhedra/cages (MOPs) with bifunctional linkers leads to soft supramolecular networks featuring both porosity and processability. However, the amorphous nature of such soft materials complicates their characterization and thus limits rational structural control. Here we demonstrate that aging is an effective strategy to control the hierarchical network of supramolecular gels, which are assembled from organic ligands as linkers and MOPs as junctions. Normally, the initial gel formation by rapid gelation leads to a kinetically trapped structure with low controllability. Through a controlled post-synthetic aging process, we show that it is possible to tune the network of the linked MOP gel over multiple length scales. This process allows control on the molecular-scale rearrangement of interlinking MOPs, mesoscale fusion of colloidal particles and macroscale densification of the whole colloidal network. In this work we elucidate the relationships between the gel properties, such as porosity and rheology, and their hierarchical structures, which suggest that porosity measurement of the dried gels can be used as a powerful tool to characterize the microscale structural transition of their corresponding gels. This aging strategy can be applied in other supramolecular polymer systems particularly containing kinetically controlled structures and shows an opportunity to engineer the structure and the permanent porosity of amorphous materials for further applications. KW - SAXS KW - Metal-organic polyhedra KW - Structural control PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-532309 DO - https://doi.org/10.1039/d1sc02883a SN - 1478-6524 SN - 1742-2183 VL - 12 IS - 38 SP - NIL_1 EP - NIL_9 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-53230 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Aliyah, K. A1 - Prehal, C. A1 - Diercks, J. S. A1 - Diklić, N. A1 - Xu, L. A1 - Ünsal, S. A1 - Appel, C. A1 - Pauw, Brian Richard A1 - Smales, Glen Jacob A1 - Guizar-Sicairos, M. A1 - Herranz, J. A1 - Gubler, L. A1 - Büchi, F. N. A1 - Eller, J. T1 - Quantification of PEFC Catalyst Layer Saturation via In Silico, Ex Situ, and In Situ Small-Angle X-ray Scattering N2 - The complex nature of liquid water saturation of polymer electrolyte fuel cell (PEFC) catalyst layers (CLs) greatly affects the device performance. To investigate this problem, we present a method to quantify the presence of liquid water in a PEFC CL using small-angle X-ray scattering (SAXS). This method leverages the differences in electron densities between the solid catalyst matrix and the liquid water filled pores of the CL under both dry and wet conditions. This approach is validated using ex situ wetting experiments, which aid the study of the transient saturation of a CL in a flow cell configuration in situ. The azimuthally integrated scattering data are fitted using 3D morphology models of the CL under dry conditions. Different wetting scenarios are realized in silico, and the corresponding SAXS data are numerically simulated by a direct 3D Fourier transformation. The simulated SAXS profiles of the different wetting scenarios are used to interpret the measured SAXS data which allows the derivation of the most probable wetting mechanism within a flow cell electrode. KW - Polymer electrolyte fuel cell KW - Water management KW - Catalyst layer KW - Representative morphology modeling KW - Small-angle X-ray scattering KW - MOUSE KW - SAXS PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-575973 DO - https://doi.org/10.1021/acsami.3c00420 SN - 1944-8244 VL - 15 IS - 22 SP - 26538 EP - 26553 PB - ACS Publications AN - OPUS4-57597 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Hodoroaba, Vasile-Dan A1 - Fontanges, R. A1 - Delvallée, A. A1 - Deumer, J. A1 - Salzmann, C. A1 - Crouzier, L. A1 - Gollwitzer, C. A1 - Klein, T. A1 - Koops, R. A1 - Sebaihi, N. A1 - Pauw, Brian Richard A1 - Smales, Glen Jacob A1 - Artous, S. A1 - Taché, O. A1 - Feltin, N. T1 - Report on full algorithm sequences for nanoparticle detection and size measurement as developed on both a physical basis and by machine learning N2 - he main objective of the nPSize project is to improve the measurement capabilities for nanoparticle size based on both measurement methods traceable to SI units and new reference materials. Two basic approaches have been used in order to develop measurement procedures resulting in traceable results of the nanoparticle size distribution: physical modelling for the methods used in the project (TSEM, SEM, AFM and SAXS) and machine learning. Physical modelling: In this part, the physical models associated with different shape measurements for the techniques TSEM, SEM, AFM and SAXS have been collected and further developed with the aim to simulate the resulting signal as measured by the individual methods. Uncertainties and traceability associated with each model were investigated and evaluated. In the following, the progress on these physical models is reported for each individual method. Machine Learning modelling: The aim of this part is to use machine learning to enable automatic measurement of nanoparticle shape from expert a-priori information only. No physical model will be used as a-priori information in this task. The accuracy and traceability of the size results obtained by each technique will be analyzed and compared with the physical modelling. A machine learning database will then be used to create automatic detection algorithms. KW - Nanoparticles KW - Particle size distribution KW - SEM KW - TSEM KW - TEM KW - SAXS KW - AFM PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546531 DO - https://doi.org/10.5281/zenodo.5807864 SP - 1 EP - 20 PB - Zenodo CY - Geneva AN - OPUS4-54653 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Aliyah, K. A1 - Berger, A. A1 - Lazaridis, T. A1 - Appel, C. A1 - Prehal, C. A1 - Menzel, A. A1 - Guizar-Sicairos, M. A1 - Smales, Glen J. A1 - Pauw, Brian Richard A1 - Gasteiger, H. A. A1 - Gubler, L. A1 - Büchi, F. N. A1 - Eller, J. T1 - Impact of Microporous Layer Composition on the Water Content in the Membrane Electrode Assembly of Polymer Electrolyte Fuel Cells N2 - Polymer electrolyte fuel cells are paramount for future emission-free mobility. One of the vital challenges for prospering commercialization of PEFCs is water management in the cells. A microporous layer (MPL) is typically positioned between the gas Diffusion layer (GDL) and the catalyst layer (CL) to boost the cell performance and facilitate water management. In this study, three different MPLs were investigated, namely, carbon black-based MPLs with different PTFE binder contents (20 wt % PTFE as a base case and 40 wt % PTFE), as well as perforated MPLs with micron-sized pores coated on the same GDL- Substrate (Freudenberg H14). The water content in the membrane, catalyst layers (CL), and MPLs was explored using operando scanning small- and wide-angle X-ray scattering (S/WAXS). At Tcell = 80 °C, relative humidity = 100%, pabs = 3 bar, the MPL with larger pores exhibits slightly higher performance than the base case, while a considerably lower cathode CL and MPL saturation levels were observed for the MPL. In contrast, the MPL with higher amounts of PTFE binder shows lower performance than the base case, with considerably higher cathode CL and MPL saturation levels. 3D representations of how the pores could be filled in the cathode CLs were obtained from operando SAXS profiles using representative structure modeling for the different materials and operating conditions. KW - Polymer electrolyte fuel cell KW - Catalyst layer saturation KW - Microporous layer saturation KW - Membrane hydration KW - Small and wide-angle scattering KW - MOUSE KW - SAXS KW - X-ray scattering KW - Energy storage materials PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-656691 DO - https://doi.org/10.1021/acsami.5c22540 SN - 1944-8244 SP - 1 EP - 17 PB - American Chemical Society (ACS) AN - OPUS4-65669 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 - 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 - Hayward, E. C. A1 - Smales, Glen Jacob A1 - Pauw, Brian Richard A1 - Takeguchi, M. A1 - Kulak, A. A1 - Hunter, R. D. A1 - Schnepp, Z. T1 - The effect of catalyst precursors on the mechanism of iron-catalysed graphitization of cellulose N2 - Iron-catalysed graphitization of biomass is a simple and sustainable route to carbons with high graphitic content. It uses abundant precursors and moderate processing temperatures and generates carbons with high porosity. Recently, it has been demonstrated that the choice of biomass precursor can have a significant impact on the textural and compositional properties of the resulting carbon. In this paper, we demonstrate that the choice of catalyst is also critical to the carbon structure. Aqueous iron(III) nitrate and iron(III) chloride convert cellulose to carbons with very different textural properties. This is due to the choice of iron catalyst changing the mechanism of cellulose decomposition and also the nature of the active graphitization catalyst. KW - Catalyst KW - Carbon materials KW - Cellulose KW - Small-angle scattering KW - Green energy KW - Graphitic carbon KW - Green synthesis PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-614800 DO - https://doi.org/10.1039/D4SU00365A SP - 1 EP - 10 PB - Royal Society of Chemistry (RSC) AN - OPUS4-61480 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 - Sänger, Johanna C. A1 - Riechers, Birte A1 - Pauw, Brian Richard A1 - Maaß, Robert A1 - Günster, Jens T1 - Microplastic response of 2PP‐printed ceramics N2 - AbstractTwo‐photon polymerization (2PP) additive manufacturing (AM) utilizes feedstocks of ceramic nanoparticles of a few nanometers in diameter, enabling the fabrication of highly accurate technical ceramic design with structural details as small as 500 nm. The performance of these materials is expected to differ from conventional AM ceramics, as nanoparticles and three‐dimensional printing at high resolution introduce new microstructural aspects. This study applies 2PP‐AM of yttria‐stabilized zirconia to investigate the mechanical response behavior under compressive load, probing the influence of smallest structural units induced by the line packing during the printing process, design of sintered microblocks, and sintering temperature and thereby microstructure. We find a dissipative mechanical response enhanced by sintering at lower temperatures than conventional. The pursued 2PP‐AM approach yields a microstructured material with an increased number of grain boundaries that proposedly play a major role in facilitating energy dissipation within the here printed ceramic material. This microplastic response is further triggered by the filigree structures induced by hollow line packing at the order of the critical defect size of ceramics. Together, these unique aspects made accessible by the 2PP‐AM approach contribute to a heterogeneous nano‐ and microstructure, and hint toward opportunities for tailoring the mechanical response in future ceramic applications. KW - Manufacturing KW - Mechanical properties KW - Microstructure KW - Plasticity KW - Zirconia: yttria stabilized PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-605176 DO - https://doi.org/10.1111/jace.19849 SN - 1551-2916 VL - 107 IS - 10 SP - 6636 EP - 6645 PB - Wiley CY - Oxford AN - OPUS4-60517 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fletcher, D. C. A1 - Hunter, R. A1 - Xia, W. A1 - Smales, Glen Jacob A1 - Pauw, Brian Richard A1 - Blackburn, E. A1 - Kulak, A. A1 - Xin, H. A1 - Schnepp, Z. T1 - Scalable synthesis of dispersible iron carbide (Fe3C) nanoparticles by ‘nanocasting’ N2 - Metal carbides have shown great promise in a wide range of applications due to their unique catalytic, electrocatalytic and magnetic properties. However, the scalable production of dispersible metal carbide nanoparticles remains a challenge. Here, we report a simple and scalable route to dispersible iron carbide (Fe3C) nanoparticles. This uses MgO nanoparticles as a removable ‘cast’ to synthesize Fe3C nanoparticles from Prussian blue (KFeIII[FeII(CN)6]). Electron tomography demonstrates how nanoparticles of the MgO cast encase the Fe3C nanoparticles to prevent sintering and agglomeration during the high-temperature synthesis. The MgO cast is readily removed with ethylenediaminetetraacetic acid (EDTA) to generate Fe3C nanoparticles that can be used to produce a colloidal ferrofluid or dispersed on a support material. KW - Small-angle scattering KW - SAXS KW - Metal carbides KW - Nanoparticles KW - Nanocasting PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-486295 DO - https://doi.org/10.1039/C9TA06876G SN - 2050-7488 SN - 2050-7496 VL - 7 IS - 33 SP - 19506 EP - 19512 PB - Royal Society of Chemistry (RSC) AN - OPUS4-48629 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -