TY - JOUR
A1 - Casali, Lucia
A1 - Carta, Maria
A1 - Michalchuk, Adam
A1 - Delogu, Francesco
A1 - Emmerling, Franziska
T1 - Kinetics of the mechanically induced ibuprofen–nicotinamide co-crystal formation by in situ X-ray diffraction
N2 - Mechanochemistry is drawing attention from the pharmaceutical industry given its potential for sustainable material synthesis and manufacture. Scaling mechanochemical processes to industrial level remains a challenge due to an incomplete understanding of their underlying mechanisms. We here show how time-resolved in situ powder X-ray diffraction data, coupled with analytical kinetic modelling, provides a powerful approach to gain mechanistic insight into mechanochemical reactions. By using the ibuprofen–nicotinamide co-crystal mechanosynthesis as a benchmark system, we investigate the behaviour of the solids involved and identify the factors that promote the reaction. As mechanochemical mechanisms become increasingly clear, it promises to become a breakthrough in the industrial preparation of advanced pharmaceuticals.
KW - Mechanochemistry
KW - Kinetics
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608820
DO - https://doi.org/10.1039/D4CP01457J
SN - 1463-9084
VL - 26
SP - 22041
EP - 22048
PB - Royal Society of Chemistry (RSC)
CY - Cambridge
AN - OPUS4-60882
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Michalchuk, Adam
T1 - On the physical processes of mechanochemically induced transformations in molecular solids
N2 - Initiating or sustaining physical and chemical transformations with mechanical force – mechanochemistry – provides an opportunity for more sustainable chemical processes, and access to new chemical reactivity.
KW - Molecular solids
KW - Transformation
KW - Destabilisation
KW - Instabilities
KW - Common phenomenon
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-621755
DO - https://doi.org/10.1039/d4cc04062g
IS - 99
SP - 1
EP - 12
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-62175
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Gugin, Nikita
A1 - Yusenko, Kirill
A1 - King, Andrew
A1 - Meyer, Klas
A1 - Al-Sabbagh, Dominik
A1 - Villajos Collado, José Antonio
A1 - Emmerling, Franziska
T1 - Lighting up industrial mechanochemistry: Real-time in situ monitoring of reactive extrusion using energy-dispersive X-ray diffraction
N2 - Mechanochemistry is an environmentally friendly synthetic approach that enables the sustainable production of a wide range of chemicals while reducing or eliminating the need for solvents. Reactive extrusion aims to move mechanochemistry from its conventional gram-scale batch reactions, typically performed in laboratory ball mills, to a continuous, large-scale process. Meeting this challenge requires in situ monitoring techniques to gain insights into reactive extrusion and its underlying processes. While the effectiveness of in situ Raman spectroscopy in providing molecular-level information has been demonstrated, our study uses energy-dispersive X-ray diffraction to monitor reactive extrusion in real time at the crystalline level. Our results provide previously unavailable control over the reactive extrusion process, promoting its perception as an industrially feasible green alternative to traditional solvent-based syntheses.
KW - Mechanochemistry
KW - Reactive extrusion
KW - Green chemistry
KW - In situ studies
KW - Time-resolved in situ
KW - TRIS
KW - Synchrotron radiation
KW - Scalable synthesis
KW - Solid-state reactions
KW - Reaction mechanisms
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-613969
DO - https://doi.org/10.1016/j.chempr.2024.07.033
VL - 10
IS - 11
SP - 1
EP - 16
PB - Elsevier B.V.
AN - OPUS4-61396
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Stawski, Tomasz
A1 - Karafiludis, Stephanos
A1 - Pimentel, Carlos
A1 - Montes-Hernández, German
A1 - Kochovski, Zdravko
A1 - Bienert, Ralf
A1 - Weimann, Karin
A1 - Emmerling, Franziska
A1 - Scoppola, Ernesto
A1 - Van Driessche, Alexander E.S.
T1 - Solution-driven processing of calcium sulfate: The mechanism of the reversible transformation of gypsum to bassanite in brines
N2 - Here, we show that calcium sulfate dihydrate (gypsum) can be directly, rapidly and reversibly converted to calcium sulfate hemihydrate (bassanite) in high salinity solutions (brines). The optimum conditions for the efficient production of bassanite in a short time (<5 min) involve the use of brines with c(NaCl) > 4 M and maintaining a temperature, T > 80 °C. When the solution containing bassanite crystals is cooled down to around room temperature, eventually gypsum is formed. When the temperature is raised again to T > 80 °C, bassanite is rapidly re-precipitated. This contrasts with the better-known behaviour of the bassanite phase in low-salt environments. In low-salinity aqueous solutions, bassanite is considered to be metastable with respect to gypsum and anhydrite, and therefore gypsum-to-bassanite conversion does not occur in pure water. Interestingly, the high-salinity transformation of gypsum-to-bassanite has been reported by many authors and used in practice for several decades, although its very occurrence actually contradicts numerical thermodynamic predictions regarding solubility of calcium sulfate phases. By following the evolution of crystalline phases with in situ and time-resolved X-ray diffraction/scattering and Raman spectroscopy, we demonstrated that the phase stability in brines at elevated temperatures was inaccurately represented in the thermodynamic databases. Most notably for c(NaCl) > 4 M, and T > 80 °C gypsum becomes readily more soluble than bassanite, which induces the direct precipitation of the latter from gypsum. The fact that these transformations are controlled by the solution provides extensive opportunities for precise manipulation of crystal formation. Our experiments confirmed that bassanite remained the sole crystalline phase for many hours before reverting into gypsum. This property is extremely advantageous for practical processing and efficient crystal extraction in industrial scenarios.
KW - Industrial and Manufacturing Engineering
KW - Strategy and Management
KW - General Environmental Science
KW - Renewable Energy, Sustainability and the Environment
KW - Building and Construction
KW - Calcium sulfate
KW - Gypsum
KW - Bassanite
KW - Scattering
KW - Raman
KW - In situ
KW - Synchrotron
KW - BESSY
KW - MySpot
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-594698
UR - https://www.sciencedirect.com/science/article/pii/S0959652624004591#appsec1
DO - https://doi.org/10.1016/j.jclepro.2024.141012
SN - 0959-6526
VL - 440
SP - 1
EP - 12
PB - Elsevier B.V.
AN - OPUS4-59469
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Zuffa, Caterina
A1 - Cappuccino, Chiara
A1 - Casali, Lucia
A1 - Emmerling, Franziska
A1 - Maini, Lucia
T1 - Liquid reagents are not enough for liquid assisted grinding in the synthesis of [(AgBr)(n-pica)]n
N2 - This study investigates the mechanochemical reactions between AgBr 3-picolylamine and 4-picolylamine. The use of different stoichiometry ratios of the reagents allows [(AgBr)(n-pica)]n and [(AgBr)2(n-pica)]n to be obtained, and we report the new structures of [(AgBr)2(3-pica)]n and [(AgBr)2(4-pica)]n which are characterized by the presence of the following: (a) infinite inorganic chains, (b) silver atom coordinated only by bromide atoms and (c) argentophilic interactions. Furthermore, we studied the interconversion of [(AgBr)(n-pica)]n/[(AgBr)2(n-pica)]n by mechanochemical and thermal properties. The in situ experiments suggest that [(AgBr)(3-pica)]n is kinetically favoured while [(AgBr)2(3-pica)]n is converted into [(AgBr)(3-pica)]n only with a high excess of the ligand. Finally, the liquid nature of the ligands is not sufficient to assist the grinding process, and the complete reaction is observed with the addition of a small quantity of acetonitrile.
KW - Mechanochemistry
KW - Complex
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-594755
DO - https://doi.org/10.1039/d3cp04791a
SN - 1463-9076
SP - 1
EP - 10
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-59475
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Heinekamp, Christian
A1 - Kneiske, Sönke
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Ahrens, Mike
A1 - Braun, Thomas
A1 - Emmerling, Franziska
T1 - A fluorolytic sol-gel route to access an amorphous Zr fluoride catalyst: A useful tool for C-F bond activation
N2 - A route to a ZrF4 catalyst active in room temperature Friedel–Crafts and dehydrofluorination reactions was developed via a fluorolytic sol–gel route, which was followed by a postfluorination step using a stream of CHClF2. The behaviour of different Zr(IV) precursors in a sol–gel reaction with anhydrous isopropanol/HF solution was investigated. The subsequent post-fluorination step was optimised in its temperature ramp and confirmed the necessity of a fluorination of the generated xerogels to obtain catalytic activity. The process is discussed in the context of the analysis of the materials using Brunauer–Emmett–Teller analysis (BET), powder X-ray diffraction (XRD), infrared spectroscopy (IR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The local structure of the amorphous catalyst was elucidated by extended X-ray absorption fine structure spectroscopy (EXAFS).
KW - Catalysis
KW - Heterogeneous catalysis
KW - C-F bond activation
KW - Postfluorination
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-593433
DO - https://doi.org/10.1039/D3CY01439H
SN - 2044-4761
SP - 1
EP - 8
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-59343
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Macchietti, Laura
A1 - Casali, Lucia
A1 - Emmerling, Franziska
A1 - Braga, Dario
A1 - Grepioni, Fabrizia
T1 - Deriving kinetic insights from mechanochemically synthesized compounds using multivariate analysis (MCR-ALS) of powder X-ray diffraction data
N2 - Kinetics information on the progress of the mechanochemical reactions is key to their understanding and subsequent scale-up. For crystalline materials, the most robust and tested method for obtaining kinetic data is the Quantitative Phase Analysis (QPA) via Rietveld refinement. In this work, we tested the feasibility of the Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) method on powder X-ray diffraction (PXRD) data of mechanochemical processes by studying the system theophylline (TP) and malonic acid (MA) in a 1 : 1 stoichiometric ratio at different milling conditions. We have highlighted the strengths and weaknesses of the MCR-ALS method, and we demonstrated why it may be an alternative route to obtain quantitative information on mechanochemical kinetics.
KW - Mechanochemistry
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-646115
DO - https://doi.org/10.1039/d3mr00013c
SN - 2976-8683
VL - 1
IS - 1
SP - 106
EP - 115
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-64611
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kadri, Lena
A1 - Casali, Lucia
A1 - Emmerling, Franziska
A1 - Tajber, Lidia
T1 - Mechanochemical comparison of ball milling processes for levofloxacin amorphous polymeric systems
N2 - This study aimed to investigate the amorphization capabilities of levofloxacin hemihydrate (LVXh), a fluoroquinolone drug, using a polymer excipient, Eudragit® L100 (EL100). Ball milling (BMing) was chosen as the manufacturing process and multiple mill types were utilized for comparison purposes. The product outcomes of each mill were analyzed in detail. The solid-state of the samples produced was comprehensively characterized by Powder X-ray Diffraction (PXRD), In-situ PXRD, Differential Scanning Calorimetry (DSC), Solid-State Fourier Transform Infrared Spectroscopy (FT-IR), and Dynamic Vapor Sorption (DVS). The crystallographic planes of LVXh were investigated by in-situ PXRD to disclose the presence or absence of weak crystallographic plane(s). The mechanism of LVXh:EL100 system formation was discovered as a two-step process, first involving amorphization of LVXh followed by an interaction with EL100, rather than as an instantaneous process. DVS studies of LVXh:EL100 samples showed different stability properties depending on the mill used and % LVXh present. Overall, a more sustainable approach for achieving full amorphization of the fluoroquinolone drug, LVXh, was accomplished, and advancements to the fast-growing world of pharmaceutical mechano- and tribo-chemistry were made.
KW - Levofloxacin
KW - Eudragit® L100
KW - Mechanochemistry
KW - Phase transformation
KW - In situ monitoring
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-611129
DO - https://doi.org/10.1016/j.ijpharm.2024.124652
SN - 0378-5173
VL - 665
SP - 1
EP - 16
PB - Elsevier B.V.
AN - OPUS4-61112
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Baláž, Matej
A1 - Birinci, Mustafa
A1 - Şentürk, Kader
A1 - Achimovičová, Marcela
A1 - Baláž, Peter
A1 - Tampubolon, Imelda Octa
A1 - Stolar, Tomislav
A1 - Bienert, Ralf
A1 - Emmerling, Franziska
A1 - Erdemoğlu, Sema
A1 - Sis, Hikmet
A1 - Erdemoğlu, Murat
T1 - Utilizing Taguchi method and in situ X-ray powder diffraction monitoring to determine the influence of mechanical activation conditions on the physico-chemical properties and Al leachability of K-feldspar
N2 - K-feldspar represents an important natural resource of potassium and aluminum. Within the framework of this study, the K-feldspar was mechanically activated in a planetary ball mill under different conditions planned according to 43 Taguchi orthogonal array experimental design. As outputs, specific surface area (SBET), median particle size (d50), amorphization degree of mineral phases , and Al recovery were used. It was found that the initial d50 value of 293 μm could be reduced to 6.7 μm and the SBET value of 4.7 m2/g could be increased up to 32.5 m2/g upon milling. Both microcline KAl3SiO8, and albite NaAl3SiO8 could be almost completely amorphized, whereas quartz SiO2 still maintained some crystallinity even under the most intensive conditions. Increasing SBET and decreasing the d50 values did not lead to a significant improvement in Al leach recovery, whereas a clear relationship between the amorphization of microcline and the recovered aluminum was found. Analysis of Variance (ANOVA) showed that increasing ball-to-powder ratio is the most beneficial for the improvement in Al recovery. In situ powder X-ray diffraction monitoring performed in an oscillation ball mill under synchrotron irradiation has shown very rapid amorphization of microcline phase at the beginning. However, amorphization of microcline was only partial after two hours of the treatment in this mill, apart from almost complete process in the planetary ball mill. In the end, regressions for the calculation of Al recovery by knowing the values of input parameters were calculated. In general, by just using mechanical activation without the subsequent roasting process that is commonly used to boost metal recoveries, it was possible to quantitatively recover aluminum from K-feldspar.
KW - Mechanochemistry
KW - Mechanical activation
KW - Design of experiments
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-611059
DO - https://doi.org/10.1016/j.jmrt.2024.08.156
SN - 2238-7854
VL - 32
SP - 3886
EP - 3895
PB - Elsevier B.V.
AN - OPUS4-61105
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Cakir, Cafer Tufan
A1 - Bogoclu, Can
A1 - Emmerling, Franziska
A1 - Streli, Christina
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Radtke, Martin
T1 - Machine learning for efficient grazing-exit x-ray absorption near edge structure spectroscopy analysis: Bayesian optimization approach
N2 - In materials science, traditional techniques for analyzing layered structures are essential for obtaining information about local structure, electronic properties and chemical states. While valuable, these methods often require high vacuum environments and have limited depth profiling capabilities. The grazing exit x-ray absorption near-edge structure (GE-XANES) technique addresses these limitations by providing depth-resolved insight at ambient conditions, facilitating in situ material analysis without special sample preparation. However, GE-XANES is limited by long data acquisition times, which hinders its practicality for various applications. To overcome this, we have incorporated Bayesian optimization (BO) into the GE-XANES data acquisition process. This innovative approach potentially reduces measurement time by a factor of 50. We have used a standard GE-XANES experiment, which serve as reference, to validate the effectiveness and accuracy of the BO-informed experimental setup. Our results show that this optimized approach maintains data quality while significantly improving efficiency, making GE-XANES more accessible to a wider range of materials science applications.
KW - Machine Learning
KW - GE-XANES
KW - Bayesian Optimization
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-603955
DO - https://doi.org/10.1088/2632-2153/ad4253
VL - 5
IS - 2
SP - 1
EP - 12
PB - IOP Publishing
AN - OPUS4-60395
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Dittmar, Stefan
A1 - Ruhl, Aki S.
A1 - Altmann, Korinna
A1 - Jekel, Martin
T1 - Settling Velocities of Small Microplastic Fragments and Fibers
N2 - There is only sparse empirical data on the settling velocity of small, non-buoyant microplastics thus far, although it is an important parameter governing their vertical transport within aquatic environments. This study reports the settling velocities of 4031 exemplary microplastic particles. Focusing on the environmentally most prevalent particle shapes, irregular microplastic fragments of four different polymer types (9–289 µm) as well as five discrete length fractions (50–600 µm) of common nylon and polyester fibers were investigated, respectively. All settling experiments were carried out in quiescent water using a specialized optical imaging setup. The method has been previously validated in order to minimize disruptive factors, e.g. thermal convection or particle interactions, and thus enable the precise measurements of the velocities of individual microplastic particles (0.003–9.094 mm/s). Based on the obtained data, ten existing models for predicting a particle’s terminal settling velocity were assessed. It is concluded that models, which were specifically deduced from empirical data on larger microplastics, fail to provide accurate predictions for small microplastics. Instead, a different approach is highlighted as a viable option for computing settling velocities across the microplastics continuum in terms of size, density and shape.
KW - Microplastics
KW - Microplastic fibers
KW - Settling velocity
KW - Sinking velocity
KW - Sedimentation
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-597455
DO - https://doi.org/10.1021/acs.est.3c09602
SN - 0013-936X
VL - 58
IS - 14
SP - 6359
EP - 6369
PB - American Chemical Society (ACS)
AN - OPUS4-59745
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Coburger, Peter
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Emmerling, Franziska
A1 - Abbenseth, Josh
T1 - Combining geometric constraint and redox non-innocence within an ambiphilic PBiP pincer ligand
N2 - The first pincer ligand featuring a strictly T-shaped pnictogen donor moiety was synthesised. The PBiP ligand's redox activity facilitates unprecedented ambiphilic bonding of the Bi centre with transition metals through the Bi(6p) orbital.
KW - EXAFS
KW - Pincer Ligand
KW - Group 15 metals
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-611113
DO - https://doi.org/10.1039/D4SC00197D
SN - 2041-6520
SP - 1
EP - 8
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-61111
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Schlögl, Johanna
A1 - Goldammer, Ole
A1 - Bader, Julia
A1 - Emmerling, Franziska
A1 - Riedel, Sebastian
T1 - Introducing AFS ([Al(SO3F)3]x) – a thermally stable, readily available, and catalytically active solid Lewis superacid
N2 - This paper introduces the thermally stable, solid Lewis superacid aluminium tris(fluorosulfate) (AFS), that is easy-to-synthesize from commercially available starting materials. Its applicability, e.g. in catalytic C–F bond activations, is shown.
KW - Lewis Acid
KW - C-F activation
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-601001
DO - https://doi.org/10.1039/D4SC01753F
SN - 2041-6520
SP - 1
EP - 7
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-60100
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Senges, Gene
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Lindič, Tilen
A1 - Gully, Tyler A.
A1 - Winter, Marlon
A1 - Radtke, Martin
A1 - Röder, Bettina
A1 - Steinhauer, Simon
A1 - Paulus, Beate
A1 - Emmerling, Franziska
A1 - Riedel, Sebastian
T1 - Unravelling highly oxidized nickel centers in the anodic black film formed during the Simons process by in situ X-ray absorption near edge structure spectroscopy
N2 - The electrofluorination after Simons has been used for the last century to produce everyday life materials. An in situ XANES investigation of the controversially debated black film apparent in the Simons process revealed high-valent nickel centers.
KW - Synchrotron
KW - BAMline
KW - XANES
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608366
DO - https://doi.org/10.1039/d3sc06081k
SN - 2041-6520
VL - 15
IS - 12
SP - 4504
EP - 4509
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-60836
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Das, Prasenjit
A1 - Chakraborty, Gouri
A1 - Friese, Nico
A1 - Roeser, Jérôme
A1 - Prinz, Carsten
A1 - Emmerling, Franziska
A1 - Schmidt, Johannes
A1 - Thomas, Arne
T1 - Heteropolyaromatic Covalent Organic Frameworks via One-Pot Multicomponent Reactions
N2 - Multicomponent reactions (MCRs) offer a platform to create different chemical structures and linkages for highly stable covalent organic frameworks (COFs). As an illustrative example, the multicomponent Povarov reaction generates 2,4-phenylquinoline from aldehydes and amines in the presence of electron-rich alkenes. In this study, we introduce a new domino reaction to generate unprecedented 2,3-phenylquinoline COFs in the presence of epoxystyrene. This work thus presents, for the first time, structural isomeric COFs produced by multicomponent domino and Povarov reactions. Furthermore, 2,3-phenylquinolines can undergo a Scholl reaction to form extended aromatic linkages. With this approach, we synthesize two thermally and chemically stable MCR-COFs and two heteropolyaromatic COFs using both domino and in situ domino and Scholl reactions. The structure and properties of these COFs are compared with the corresponding 2,4-phenylquinoline-linked COF and imine-COF, and their activity toward benzene and cyclohexane sorption and separation is investigated. The position of the pendant phenyl groups within the COF pore plays a crucial role in facilitating the industrially important sorption and separation of benzene over cyclohexane. This study opens a new avenue to construct heteropolyaromatic COFs via MCR reactions.
KW - COF
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-604038
DO - https://doi.org/10.1021/jacs.4c02551
SP - 1
EP - 9
PB - American Chemical Society (ACS)
AN - OPUS4-60403
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Béalu, Zoé
A1 - Walther, Johanna
A1 - Abusafia, Attaallah
A1 - Altmann, Korinna
A1 - Meurer, Maren
A1 - Gretzschel, Oliver
A1 - Schäfer, Michael
A1 - Steinmetz, Heidrun
T1 - Removal of Organic Micropollutants and Microplastics via Ozonation Followed by Granular Activated Carbon Filtration
N2 - Discharge from Wastewater Treatment Plants (WWTPs) can result in the emission of organic micropollutants (OMPs) and microplastics (MPs) into the aquatic environment. To prevent this harmful release, a pilot plant consisting of an ozonation followed by a granular activated carbon (GAC) filter was operated at a WWTP in Germany, and its side-effects on the concentrations of nitrogen (N) and phosphorous (P) compounds were measured. Over 80% of OMPs and transformation products were removed during the operating time (around 6000 bed volumes) no matter the ozone dose (from around 0.1 to 0.5 mgO3/mgDOC), except for Diatrizoic acid, whose breakthrough appeared at 3500 BV. Formation of the oxidation by-product, NDMA, increased with higher ozone doses, but the concentration remained below 100 ng/L. Bromate was formed at a higher ozone dose (0.4 mgO3/mgDOC) but at a low concentration—below 10 µg/L. The MP particles detected in the inflow (PE, SBR, PP, and PS) were effectively eliminated to a high degree, with a removal rate of at least 92%. Carbon parameters (COD, DOC, and SAC254) were removed further by the pilot plant, but to different extents. As expected, nitrate was formed during ozonation, while nitrite’s concentration decreased. Further, nitrite decreased and nitrate increased within the GAC filter, while ammonium was eliminated by at least 90%. Total P concentration decreased after the pilot, but the concentration of PO4-P increased.
KW - Microplastics
KW - TED-GC/MS
KW - Granular Activated Carbon Filtration
KW - Removal of Organic Micropollutants
KW - Wastewater treatment plant
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-615209
DO - https://doi.org/10.3390/environments11110241
VL - 11
IS - 11
SP - 1
EP - 38
PB - MDPI AG
AN - OPUS4-61520
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, Hans R.
A1 - Weidner, Steffen
T1 - Ring-ring equilibration (RRE) of cyclic poly(L-lactide)s by means of cyclic tin catalysts
N2 - With 2,2-dibutyl-2-stanna-1,3-dithiolane (DSTL) and 2-stanna-1,3-dioxa-4,5,6,7-dibenzoxepane (SnBiPh) as catalysts ring-expansion polymerizations (REP) were performed either in 2 M solution using three different solvents and two different temperatures or in bulk at 140 and 120 ◦C. A kinetically controlled rapid REP up to weight average molecular masses (Mẃs) above 300 000 was followed by a slower degradation of the molecular masses at 140 ◦C, but not at 120 ◦C Furthermore, a low molecular mass cyclic poly(L-lactide) (cPLA) with a Mn around 16 000 was prepared by polymerization in dilute solution and used as starting material for ring-ring equilibration at 140 ◦C in 2 M solutions. Again, a decrease of the molecular mass was detectable, suggesting that the equilibrium Mn is below 5 000. The degradation of the molecular masses via RRE was surprisingly more effective in solid cyclic PLA than in solution, and a specific transesterification mechanism involving loops on the surface of crystallites is proposed. This degradation favored the formation of extended-ring crystallites, which were detectable by a “saw-tooth pattern” in their MALDI mass spectra.
KW - Organic Chemistry
KW - Polymers and Plastics
KW - MALDI-TOF MS
KW - Materials Chemistry
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-593819
DO - https://doi.org/10.1016/j.eurpolymj.2024.112765
SN - 0014-3057
VL - 206
SP - 1
EP - 8
PB - Elsevier B.V.
AN - OPUS4-59381
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Dalgic, Mete-Sungur
A1 - Weidner, Steffen
T1 - Solvent-free sample preparation for matrix-assisted laserdesorption/ionization time-of-flight mass spectrometry ofpolymer blends
N2 - Solvent-free sample preparation offers some advantages over solvent-based techniques, such as improved accuracy, reproducibility and sensitivity, for matrix-assisted laser desorption/ionization (MALDI) analysis. However, little or no information is available on the application of solvent-free techniques for the MALDI analysis of polymer blends. Solvent-free sample preparation by ball milling was applied with varying sample-to-matrix ratios for MALDI time-of-flight mass spectrometry analysis of various polymers, including polystyrenes, poly(methyl methacrylate)s and poly(ethylene glycol)s. The peak intensity ratios were compared with those obtained after using the conventional dried droplet sample preparation method. In addition, solvent-assisted milling was also applied to improve sample homogeneities.
Depending on the sample preparation method used, different peak intensity ratios were found, showing varying degrees of suppression of the signal intensities of higher mass polymers. Ball milling for up to 30 min was required to achieve constant intensity ratios indicating homogeneous mixtures. The use of wet-assisted grinding to improve the homogeneity of the blends was found to be disadvantageous as it caused partial degradation and mass-dependent segregation of the polymers in the vials.The results clearly show that solvent-free sample preparation must be carefully considered when applied to synthetic polymer blends, as it may cause additional problems with regard to homogeneity and stability of the blends.
KW - MALDI TOF MS
KW - Sample preparation
KW - Polymer blends
KW - Solvent-free
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-598570
DO - https://doi.org/10.1002/rcm.9756
SN - 0951-4198
VL - 38
IS - 12
SP - 1
EP - 9
PB - Wiley online library
AN - OPUS4-59857
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H.
A1 - Weidner, Steffen
A1 - Scheliga, F.
T1 - Polycondensation of poly(L-lactide) alkyl esters combined with disproportionation and symproportionation of the chain lengths
N2 - Ring-opening polymerizations (ROPs) of l-lactide (LA) were performed with ethyl l-lactate or 11-bromoundecanol as initiators (In) and tin(II) ethyl hexanoate (SnOct2) as catalyst (Cat) using four different LA/In ratios (20/1, 40/1, 60/1, and 100/1). One series of ROPs was conducted in bulk at 120 °C, yielding PLAs with low dispersities (Ð ~ 1.2–1.4), and a second series was conducted in bulk at 160 °C, yielding higher dispersities (Ð ~ 1.3–1.9). Samples from both series were annealed for 1 or 14 days at 140 °C in the presence of SnOct2. Both polycondensation and disproportionation reactions occurred, so that all four samples tended to form the same type of molar mass distribution below 10,000 Da, regardless of their initially different number average molar masses (Mn). Both initiators gave nearly identical results. The thermodynamic control of all reversible transesterification processes favored the formation of crystallites composed of chains with a Mn around 3500–3700, corresponding to a crystal thickness of 10–13 nm.
KW - Polylactide
KW - MALDI-TOF MS
KW - Crystalinity
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-600081
DO - https://doi.org/10.1002/pol.20240118
SN - 2642-4150
SP - 1
EP - 12
PB - Wiley
AN - OPUS4-60008
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H.
A1 - Weidner, Steffen
A1 - Meyer, A.
T1 - Syntheses of high molecular mass polyglycolides via ring-opening polymerization with simultaneous polycondensation (ROPPOC) by means of tin and zinc catalysts
N2 - Glycolide was polymerized in bulk by means of four different ROPPOC catalysts: tin(II) 2-ethylhexanoate (SnOct2), dibutyltin bis(pentafluoro-phenoxide) (BuSnOPF),zinc biscaproate (ZnCap), and zinc bis(pentafluoro-phenyl sulfide) (ZnSPF). The temperature was varied between 110 and 180°C and the time between 3 h and 7 days. For the few polyglycolides (PGAs) that were soluble extremely high molecular masses were obtained. The MALDI TOF mass spectra had all a low signal-to-noise ration and displayed the peaks of cyclic PGAs with a“saw-tooth pattern ”indicating formation of extended-ring crystallites in the mass range below m/z 2500. The shape of DSC curves varied considerably with catalyst and reaction conditions, whereas the long-distance values measured by SAXS were small and varied little with the polymeriza-tion conditions.
KW - MALDI TOF MS
KW - Polyglycolide
KW - Crystalinity
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-598221
DO - https://doi.org/10.1002/pat.6365
VL - 35
IS - 4
SP - 1
EP - 10
PB - John Wiley & Sons Ltd.
AN - OPUS4-59822
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H.
A1 - Weidner, Steffen
T1 - Low Molar Mass Cyclic Poly(L-lactide)s: Separate Transesterification Reactions of Cycles and Linear Chains in the Solid State
N2 - L-Lactide (LA) was polymerized with neat tin(II) 2-ethylhexanoate (SnOct2) in toluene at 115 °C at low concentration with variation of the LA/Cat ratio. Cyclic polylactides (cPLAs) with number average molecular weights (Mn) between 7 000 and 17 000 were obtained. MALDI-TOF mass spectrometry also revealed the formation of a few percent of linear chains. Crystalline cPLAs with Mn around 9 000 and 14 000 were annealed at 140 °C in the presence of ScOct2 or dibutyl-2-stanna-1,3-dithiolane (DSTL). Simultaneously, crystallites of extended linear chains and crystallites of extended cycles were formed regardless of the catalyst, indicating that transesterification reaction proceeded different for linear chains and for cycles, governed by thermodynamic control. The formation of extended chain crystallites with low dispersity indicates the existence of symproportionation of short and long chains. A complementary experiment was carried out with a PLA ethyl ester composed mainly of linear chains with a small fraction of cycles
KW - Polylactide
KW - MALDI-TOF MS
KW - Annealing
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-606228
DO - https://doi.org/10.1039/D4SM00567H
SN - 1744-6848
SP - 1
EP - 12
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-60622
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Weidner, Steffen
A1 - Meyer, A.
A1 - Kricheldorf, H.
T1 - Transformation of poly(L-lactide) crystals composed of linear chains into crystals composed of cycles
N2 - A poly(L-lactide) with a trifluoroethyl ester end group and an average degree of polymerization (DP) of 50 was synthesized by ROP of L-lactide initiated with trifluoroethanol. Small-angle X-ray scattering (SAXS) in combination with differential scanning calorimetry (DSC) measurements revealed an average crystal thickness of 13 nm, corresponding to 45 repeat units. This suggests that most crystallites were formed by extended PLA chains, and both flat surfaces were covered by CF3 groups. The crystalline PLAs were annealed at 140 or 160 °C in the presence of two catalysts: tin(II) 2-ethylhexanoate, (SnOct2) or dibutyltin bis(pentafluorophenoxide) (BuSnPhF). The chemical reactions, such as polycondensation and cyclization, proceeded in the solid state and were monitored by matrix-assisted laser desorption/ionization time-offlight (MALDI TOF) mass spectrometry and gel permeation chromatography (GPC) measurements. Under optimal conditions a large fraction of linear chains was transformed into crystallites composed of extended cycles. Additionally, MALDI TOF MS analysis of GPC fractions from samples annealed for 28 or 42 days detected chain elongation of the linear species up to a factor of 20.
KW - Polylactide
KW - MALDI-TOF MS
KW - Crystalinity
KW - Transesterification
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-597250
DO - https://doi.org/10.1039/D3PY01370G
SN - 1759-9954
VL - 15
IS - 12
SP - 1173
EP - 1181
PB - Royal Society for Chemistry
AN - OPUS4-59725
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H.
A1 - Weidner, Steffen
A1 - Meyer, A.
T1 - About alcohol-initiated polymerization of glycolide and separate crystallization of cyclic and linear polyglycolides
N2 - Alcohol-initiated polymerizations of glycolide (GL) catalyzed by tin(II) 2-ethylhexanoate (SnOct2) were carried out in bulk with variation of GA/In ratio, temperature and time. Due to a rather strong competition of cyclization polyglycolide (PGA) free of cycles were never obtained. When the cyclic catalysts 2,2-dibutal-2-stanna − 1,3-dithiolane (DSTL) or 2-stanna 1,3-dioxo-4,5,6,7 bibenzepane (SnBiph) were used in combination with 1,4-butanediol the influence of cyclization was even stronger. Furthermore, the degrees of polymerization were higher than the GA/alcohol ratio due to rapid polycondensation in the solid state. At 160 °C or below, the matrixassisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectra indicated separate crystallization of low molar mass cyclic and linear PGAs from the same reaction mixture (also observed for poly(L-lactide)s).
KW - MALDI TOF MS
KW - Polyglycolide
KW - Ring opening polymerization
KW - Cyclization
KW - Crystallization
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607282
DO - https://doi.org/10.1016/j.polymer.2024.127440
SN - 0032-3861
VL - 309
SP - 1
EP - 9
PB - Elsevier Ltd.
AN - OPUS4-60728
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H.
A1 - Weidner, Steffen
A1 - Meyer, A.
T1 - Syntheses of Polyglycolide via Polycondensation: A Reinvestigation
N2 - The Na salt of chloroacetic acid is condensed in suspension. Furthermore,glycolic acid is condensed in bulk or in concentrated solution by means of SnCl2 or 4-toluene sulfonic acid (TSA) as catalysts. The temperatures are varied from 160 to 200°C and the time from 1 to 5 days. Low molar mass cyclic poly(glycolic acid) (PGA) is detected by means of matrix-assisted laser desorption ionization time-of-flight (MALDI TOF) mass spectrometry in most PGAs. A predominance of certain cycles having an even number of repeat units is observed suggesting a thermodynamically favored formation of extended-ring crystals. Extremely high melting temperatures (up to 237.5°C)and high melting enthalpies are found for polycondensations with TSA in 1,2-dichlorobenzene.
KW - MALDI TOF MS
KW - Polycondensation
KW - Polyglycolide
KW - Cyclization
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-596856
DO - https://doi.org/10.1002/macp.202300397
IS - 2300397
SP - 1
EP - 7
PB - Wiley VHC-Verlag
AN - OPUS4-59685
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Weidner, Steffen
A1 - Scheliga, Felix
A1 - Kricheldorf, Hans R.
T1 - Polycondensation, Cyclization and Disproportionation of Solid Poly(L-lactide) Trifluoroethyl Esters and the Simultaneous Formation of Extended Chain Crystals and Extended Ring Crystals
N2 - Two poly(L-lactide)s (PLAs) with a degree of polymerization (DP) of 20 or 100 were prepared by trifluoroethanol-initiated ring-opening polymerization (ROP) catalyzed by tin(II) 2-ethyl hexanoate (SnOct2). These PLAs were annealed at 140 ◦C or at 160 ◦C in the presence of SnOct2, and the changes in topology and molecular weight distribution (MWD) were monitored by matrix-assisted laser desorption/ionization time-of flight (MALDI TOF) mass spectrometry and gel permeation chromatography (GPC). For the PLA with a DP 20, the main reaction was polycondensation combined with higher dispersities. In the case of the DP 100, PLA polycondensation was combined with disproportionation and the formation of a new MWD maximum around m/z 3500. In addition, extensive cyclization occurred, and the resulting cyclic PLAs crystallized separately from the linear chains in the form of extended ring crystals. These results also suggest that both extended chain and extended ring crystals posses the same crystal thickness as a result of thermodynamically controlled transesterification in the solid state.
KW - Polycondensation
KW - MALDI
KW - Polylactide
KW - Cyclization
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-616441
DO - https://doi.org/10.1016/j.polymer.2024.127800
VL - 315
SP - 1
EP - 9
PB - Elsevier Ltd.
AN - OPUS4-61644
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, Hans R.
A1 - Weidner, Steffen
A1 - Meyer, A.
T1 - About Polycondensation, Disproportionation, and Cyclization of Acetylated Poly(L-Lactide) Esters
N2 - L-lactide (LA) is polymerized with ethyl L-lactate or trifluoroethanol as initiators (LA/In = 30/1), and the resulting poly(L-lactide) esters are acetylated with acetic anhydride. The acetylated PLA esters are mixed with SnOct2, dibutyltin bis(4-chlorophenoxide), or dibutyltin bis(pentafluorophenoxide) in solution and crystallized at 120 °C. The doped crystals are annealed at 140 °C or at 160 °C for 7, 14, and 28 days, and the chemical modifications that occurred in the solid state are monitored by matrix-assisted laser desorption/ionization time-of-flight (MALDI TOF) mass spectrometry, gel permeation chromatography (GPC), and differential scanning calorimetry (DSC) measurements. All catalysts promoted polycondensation, while no significant formation of cycles is observed. However, in the presence of SnOct2, disproportionation of chains occurred upon annealing at 120 or 140 °C, and crystallites consisting of extended chains with Mn values ≈3500 – 3600 and low dispersities (Ð < 1.5) are formed.
KW - MALDI-TOF MS
KW - Polycondensation
KW - Polylactides
KW - Transesterifcation
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630349
DO - https://doi.org/10.1002/macp.202400175
SN - 1521-3935
VL - 225
IS - 19
PB - Wiley VHC-Verlag
AN - OPUS4-63034
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Weidner, Steffen
A1 - Meyer, A.
A1 - Falkenhagen, Jana
A1 - Kricheldorf, H. R.
T1 - Polycondensations and Cyclization of Poly(L-lactide) Ethyl Esters in the Solid State
N2 - The usefulness of seven different Tin catalysts, Bismuth subsalicylate and Titan tetra(ethoxide) for the polycondensation of ethyl L-lactate (ELA) was examined at 150 °C/6 d. Dibutyltin bis(phenoxides) proved to be particularly effective. Despite the low reactivity of ELA, weight average molecular masses (Mw) up to 12 500 were found along with partial crystallization. Furthermore, polylactides (PLAs) of similar molecular masses were prepared via ELA-initiated ROPs of L-lactide by means of the four most effective polycondensation catalysts. The crystalline linear PLAs were annealed at 140 or 160 °C in the presence of these catalysts. The consequences of the transesterification reactions in the solid PLAs were studied by means of matrix-assisted laser desorption/ionization (MALDI TOF) mass spectrometry, gel permeation chromatography (GPC) and small-angle X-ray scattering (SAXS). The results indicate that polycondensation and formation of cycles proceed in the solid state via formation of loops on the surface of the crystallites. In summary, five different transesterification reactions are required to explain all results.
KW - Polylactide
KW - MALDI-TOF MS
KW - Crystalinity
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-592934
DO - https://doi.org/10.1039/d3py01232h
SN - 1759-9962
VL - 15
IS - 2
SP - 71
EP - 82
PB - RSC Publ.
CY - Cambridge
AN - OPUS4-59293
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Weidner, Steffen
A1 - Meyer, A.
A1 - Kricheldorf, H.
T1 - Cyclic polyglycolides via ring-expansion polymerization with cyclic tin catalysts
N2 - Glycolide was polymerized in bulk with two cyclic catalysts − 2,2-dibutyl-2-stanna-1,3-dithiolane (DSTL) and 2-stanna-1,3-dioxa-4,5,6,7-dibenzepane (SnBiph). The monomer/initiator ratio, temperature (140 – 180 °C) and time (1–––4 days) were varied. The MALDI TOF mass spectra exclusively displayed peaks of cyclic polyglycolide (PGA) and revealed an unusual “saw-tooth pattern” in the mass range below m/z 2 500 suggesting formation of extended ring crystallites. The DSC measurements indicated increasing crystallinity with higher temperature and longer time, and after annealing for 4 d at 160 °C a hitherto unknown and unexpected glass transition was found in the temperature range of 170–185 °C. Linear PGAs prepared by means of metal alkoxides under identical conditions did not show the afore-mentioned features of the cyclic PGAs, neither in the mass spectra nor in the DSC measurements. All PGAs were also characterized by SAXS measurements, which revealed relatively small L-values suggesting formation of thin crystallites in all cases with little influence of the reaction conditions.
KW - Polyglycolide
KW - MALDI-TOF MS
KW - Ring-expansion polymerization
KW - Crystals
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595541
DO - https://doi.org/10.1016/j.eurpolymj.2024.112811
SN - 0014-3057
VL - 207
SP - 1
EP - 9
PB - Elsevier Ltd.
AN - OPUS4-59554
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Reigl, Selina
A1 - Van Driessche, Alexander
A1 - Stawski, Tomasz
A1 - Koltzenburg, Sebastian
A1 - Kunz, Werner
A1 - Kellermeier, Matthias
T1 - Sustainable Pathways for the Synthesis of Calcium Sulfate Hemihydrate
N2 - Calcium sulfate, and especially its hemihydrate form (bassanite), is crucial in the construction industry, primarily used as a hydraulic binder in cements, mortars, and wallboards. Because of the rapid transformation of bassanite into thermodynamically stable gypsum (calcium sulfate dihydrate) upon contact with water, natural deposits are scarce, rendering it one of the most extensively produced inorganic materials worldwide. Currently, bassanite is derived from mined or waste gypsum through a thermal dehydration process, which is energy-intensive and costly. As sustainability has become a key target for industrial processes and products, a series of studies aiming to increase the energy efficiency and reduce the carbon footprint of bassanite production was published recently. Two primary approaches are pursued: conversion of gypsum and direct precipitation of bassanite from solution. In both cases, organic solvents, (specific) additives and/or elevated temperatures have been used to control the activity/availability of water in the reaction medium and thus direct phase selection towards bassanite. This review offers a comprehensive overview of alternative bassanite production methods, critically examining their benefits, potential downsides, and overall impact on
the sustainability of industrial-scale use.
KW - Calcium sulfate
KW - Gypsum
KW - Bassanite
KW - Recycling
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630657
DO - https://doi.org/10.1002/anie.202415161
SN - 1521-3773
SP - 1
EP - 20
PB - Wiley VHC-Verlag
AN - OPUS4-63065
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Omar, Hassan
A1 - Ahmadi, Shayan
A1 - Szymoniak, Paulina
A1 - Schönhals, Andreas
T1 - Molecular Mobility of Thin Films of Poly (bisphenol-A carbonate) Capped and with one Free Surface: From Bulk-like Samples down to the Adsorbed Layer
N2 - The molecular mobility of thin films of poly(bisphenol A carbonate) (PBAC) was systematically investigated using broadband dielectric spectroscopy, employing two distinct electrode configurations. First, films were prepared in a capped geometry between aluminum electrodes employing a crossed electrode capacitor (CEC) configuration, down to film thicknesses of 40 nm. The Vogel temperature, derived from the temperature dependence of relaxation rate of the α-relaxation, increases with decreasing film thickness characterized by an onset thickness. The onset thickness depends on the annealing conditions, with less intense annealing yielding a lower onset thickness. Additionally, a broadening of the β-relaxation peak was observed with decreasing thickness, attributed to the interaction of phenyl groups with thermally evaporated aluminum, resulting in a shift of certain relaxation modes to higher temperatures relative to the bulk material. A novel phenomenon, termed the slow Arrhenius process (SAP), was also identified in proximity to the α-relaxation temperature.
For films with thicknesses below 40 nm, nanostructured electrodes (NSE) were utilized, incorporating nanostructured silica spacers to establish a free surface with air. This free surface causes an enhancement in the molecular mobility for the 40 nm sample, preserving the β-relaxation as a distinct peak. The α-relaxation was detectable in the dielectric loss down to 18 nm, shifting to higher temperatures as film thickness is decreased. Notably, the onset thickness for the increase in Vogel temperature was lower in the NSE configuration compared to the CEC setup, attributed to the presence of the polymer-air interface.
KW - Thin polymer films
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-623422
DO - https://doi.org/10.1039/d4sm01238k
SN - 1744-6848
VL - 21
IS - 2
SP - 241
EP - 254
PB - RSC
AN - OPUS4-62342
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - John, Elisabeth
A1 - Jakob, Cordula
A1 - Pott, Ursula
A1 - Sando, Mona
T1 - Repeatability and reproducibility challenges of isothermal heat flow calorimetry with in situ mixing
N2 - Isothermal heat flow calorimetry evaluates heat development during binder reactions. It distinguishes between in situ calorimetry, where mixing occurs within the device, and ex situ calorimetry, involving externally mixed samples. Despite ex situ calorimetry being a standard method in binder research, in situ calorimetry is underutilized. This paper aims to promote its adoption by summarizing challenges related to repeatability and reproducibility and offering solutions. The initial section addresses repeatability issues caused by preventable errors, providing a structured guide for experimental design. It was found that water leakage had minimal impact, and sample size is crucial for data robustness. The second section examines operational challenges, revealing that frictional heating, affecting recorded heat, can be minimized with an optimized mixing protocol. The final part highlights that significant errors in measured data stem from signal delay and heat loss, offering methods to correct these issues for improved reproducibility in in situ calorimetric experiments.
KW - In situ calorimetry
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-628431
DO - https://doi.org/10.1016/j.cemconres.2025.107872
SN - 1873-3948
VL - 194
SP - 1
EP - 11
PB - Elsevier Ltd.
AN - OPUS4-62843
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Xu, Q.
A1 - Szymoniak, Paulina
A1 - Kolmangadi, Mohamed A.
A1 - Yang, Z.
A1 - Wang, S.
A1 - Gao, Y.
A1 - Shang, J.
A1 - Hunger, J.
A1 - Aldiyarov, A.
A1 - Schönhals, Andreas
A1 - Ge, Y.
A1 - Qi, Z.
T1 - Molecular engineering of supramolecular polymer adhesive with confined water and a single crown ether
N2 - Here, we report a water-induced supramolecular polymer built from confined structural water and an intrinsic amphiphilic macrocyclic self-assembly in a nanophase separated structure. The newly designed crown ether macrocycle, featuring strong hydrophilic hydrogen bonding receptor selenoxide and a synergistical hydrophobic selenium-substituted crown core, confines the structural water in a segregated, interdigitated architecture. Although water molecules typically freeze around 0 °C, the confined structural water in this supramolecular polymer remains in a liquid-like state down to 80 °C. Previous studies suggest that multiple crown ether units are needed to generate structural water. However, here, one unit is sufficient to control the formation and disappearance of structural water and consequent supramolecular polymerization. Typically, the DC conductivity of water shows Arrhenius temperature dependency (lnσDC ∝ 1/T). In contrast, this new crown unit maintains water in confined states, which exhibit a Vogel/Fulcher/Tammann behavior (lnσDC ∝ 1/(T-T0)) at temperatures above the glass transition temperature. Moreover, this water-induced supramolecular polymer exhibits remarkable adhesion properties to hydrophilic surfaces and maintains tough adhesion at low temperatures. These findings show how a single small macrocycle can govern the complex structure and functionality of water in supramolecular systems.
KW - Supramolecular polymerization
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-623631
DO - https://doi.org/10.1039/D4SC06771A
SN - 2041-6539
VL - 16
SP - 1
EP - 9
PB - RSC
AN - OPUS4-62363
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Mishmastnehi, Moslem
A1 - Stawski, Tomasz M.
A1 - Eftekhari, Negar
A1 - Schneider, Kathrin P.
A1 - Vaccaro, Carmela
A1 - Aghajani, Iman
A1 - Grbanovic, Ana Marija
A1 - Korn, Lorenz
T1 - Unveiling the craftsmanship and knowledge behind iranian stuccoes (11th–14th centuries): New insights from an archaeometric perspective
N2 - Gypsum-based stucco decorations of 47 monuments in Iran, from the Seljuq to the Ilkhanid period (11th-14th centuries), were studied by multimodal analytical methods, including X-ray diffraction, X-ray fluorescence, scanning electron microscopy and image analysis to evaluate their composition properties. The assessment of results shows that stucco masters in those periods exerted control over the setting process of the gypsum-paste and its microstructure by adjusting water-to-plaster ratio, fine-clay addition, and by means of mechanical processing. Furthermore, the presence of anhydrite in the composition of stucco decorations located in the hot-desert climate of Iran provides evidence for the probability of gypsum-anhydrite transition, which has technical and preservation consequences for this less-investigated type of cultural materials.
KW - Gypsum
KW - Diffraction
KW - Anhydrite
KW - Calcium sulfate
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-628406
DO - https://doi.org/10.1016/j.jas.2025.106199
SN - 1095-9238
VL - 177
SP - 1
EP - 13
PB - Elsevier B.V.
AN - OPUS4-62840
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Senbill, Haytham
A1 - Gangan, Amr
A1 - Saeed, Ahmed M.
A1 - Gad, Mohammed E.
A1 - Zeb, Jehan
A1 - Fahmy, Alaa
T1 - Effects of copper/graphene oxide core-shell nanoparticles on Rhipicephalus ticks and their detoxification enzymes
N2 - Nanopesticides have been recently introduced as novel pesticides to overcome the drawbacks of using traditional synthetic pesticides. The present study evaluated the acaricidal activity of Copper/Graphene oxide core-shell nanoparticles against two tick species, Rhipicephalus rutilus and Rhipicephalus turanicus. The Copper/Graphene oxide core-shell nanoparticles were synthetized through the solution plasma (SP) method under different conditions. The nanoparticles synthesized at 180 W and 45 min were highly toxic to Rh. rutilus and Rh. turanicus, with 50% lethal concentration (LC50) values of 248.1 and 195.7 mg ml−1, respectively, followed by those which were synthesized at 120 W/30 mins (LC50 = 581.5 and 526.5 mg ml−1), 120 W/15 mins (LC50 = 606.9 and 686.7 mg ml−1), and 100/45 mins (LC50 = 792.9 and 710.7 mg ml−1), after 24 h of application. The enzyme assays revealed that 180 W/45 min treatment significantly inhibited the activity of acetylcholinesterase (115 ± 0.81 and 123 ± 0.33 U/ mg protein/min) and superoxide dismutase (290 ± 0.18 and 310 ± 0.92 U/ mg protein/min) in Rh. rutilus and Rh. turanicus, respectively, as compared with the negative control. The results also revealed a significantly increased catalase activity (895 ± 0.37 and 870 ± 0.31 U/ mg protein/min) in Rh. rutilus and Rh. turanicus, respectively. The above results indicated that Copper/Graphene oxide core-shell nanoparticles could be a promising alternatives for the management of ticks.
KW - Copper/graphene oxide
KW - Nanopesticides
KW - Rhipicephalus rutilus
KW - Rhipicephalus turanicus
KW - Acetylcholinesterase
KW - Antioxidants
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-629359
DO - https://doi.org/10.1038/s41598-025-86560-4
SN - 2045-2322
VL - 15
SP - 1
EP - 12
PB - Springer Nature
CY - London
AN - OPUS4-62935
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Szymoniak, Paulina
A1 - Juranyi, F.
A1 - Kruteva, M.
A1 - Zorn, R.
A1 - Schönhals, Andreas
T1 - Low-Frequency Vibrational Density of States of Nanophase- Separated Poly(n‑alkyl methacrylate)s: Confined Phonons and Relationship to Specific Heat
N2 - This study investigates the low-frequency vibrational Density of states of nanophase-separated poly(n-alkyl methacrylate)s (PnMAs) and its relationship to specific heat. This system undergoes a nanophase separation for n > 1 in alkyl side chain-rich domains and a backbone-rich matrix. Using inelastic neutron scattering, the low-frequency vibrational density of states (Boson peak, BP) of PnMAs with varying alkyl side chain lengths (methyl, butyl, hexyl, and octyl) is measured. The results reveal that the BP shifts to higher frequencies with increasing side chain length reaching a maximum. This result indicates a counterbalance of confinement effects and the scattering of the matrix. The behavior of the Boson peak of the PnMAs is compared to other nanophase-separated systems, such as Janus-polynorbornenes and hexakis(n-alkyloxy)triphenylene discotic liquid crystals. The study also explores the connection between the BP and specific heat capacity, showing a linear relationship between the maximum frequency of the BP and the maximum temperature of the specific heat capacity anomaly. Moreover, from the measured vibrational density of states, the specific heat capacity is calculated and compared to experimental results. The comparison reveals qualitative agreement between the calculated and experimental data. These findings provide evidence for the sound wave interpretation of the Boson peak.
KW - Inelastic Neutron Scattering
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-636928
DO - https://doi.org/10.1021/acs.macromol.5c00898
SN - 1520-5835
SP - 1
EP - 12
PB - ACS Publications
AN - OPUS4-63692
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Gawek, Marcel
A1 - Szymoniak, Paulina
A1 - Hülagü, Deniz
A1 - Hertwig, Andreas
A1 - Schönhals, Andreas
T1 - Molecular Mobility of Thin Films and the Adsorbed Layer of Poly(2-vinylpyridine)
N2 - The molecular dynamics of thin films and the adsorbed layer of poly(2-vinylpyridine) (P2VP) were investigated using broadband dielectric spectroscopy (BDS) and spectroscopic ellipsometry. Thin films of P2VP were prepared on silicon substrates and characterized to understand the influence of film thickness on the thermal glass transition temperature (Tg) and molecular mobility. The ellipsometric study revealed a decrease in Tg with decreasing film thickness, attributed to the enhanced mobility at the polymer/air interface. The adsorbed layer, prepared via the solvent leaching approach, exhibited a higher Tg compared to the bulk, indicating reduced molecular mobility due to strong polymer substrate interactions. The dielectric measurements were carried out in two different electrode configurations, crossed electrode capacitors (CEC) and nanostructured electrodes (NSE), where the latter allows for a free surface layer at the polymer/air interface. The relaxation rates of the α-relaxation measured in the CEC geometry collapse into one chart independent from the film thickness. For the thin films measured in the NSE arrangement the relaxation rates slow down with decreasing film thickness which was discussed as related to a stronger interaction of the P2VP segments with the native SiO2 at the surface of the silicon substrate compared to aluminum. It is worth to note that the effect of the enhanced mobility at the polymer/air interface is not observed in the dielectric measurements. BDS measurements in NSE geometry identified an additional relaxation process (α*-relaxation) in thin films, which was more pronounced in the adsorbed layer. This process is hypothesized to be related to molecular fluctuations within the adsorbed layer including the adsorption/desorption dynamics of segments or to a Slow Arrhenius Process (SAP) related to the equilibration dynamics deep in the glassy state.
KW - Thin polymer films
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-637181
DO - https://doi.org/10.1039/d5sm00539f
SN - 1744-6848
SP - 1
EP - 12
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-63718
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Szymoniak, Paulina
A1 - Kolmangadi, Mohamed A.
A1 - Böhning, Martin
A1 - De Souza, N. R.
A1 - Juranyi, F.
A1 - Zorn, R.
A1 - Schönhals, Andreas
T1 - Inelastic and Quasielastic Neutron Scattering on Polynorbornenes with Bulky Carbocyclic Side groups
N2 - This study investigates the molecular mobility and vibrational properties of polynorbornenes with bulky carbocyclic side groups using inelastic and quasielastic neutron scattering techniques. The polymers, synthesized via metathesis and addition polymerization, exhibit varying degrees of microporosity, which ignificantly influences their gas separation performance. By inelastic neutron scattering experiments, it could be shown that all considered polymers have excess contributions to the low frequency vibrational density of states known as the Boson peak. The maximum frequency of the Boson peak correlates to the microporosity of the polymers.
This correlation supports the sound wave interpretation of the Boson peak, suggesting that the microporous structure enhances the compressibility of the material at a microscopic length scale. The molecular mobility, particularly the methyl group rotation, was characterized using elastic scans and quasielastic neutron scattering. The study revealed a temperature dependent relaxation process, with the onset of molecular fluctuations observed around 200 K for the polymer containing methyl groups. For the polymer having no methyl groups only elastic scattering is observed. The methyl group rotation was analyzed in terms of a jump diffusion in a threefold potential with three equivalent energy minima. This leads to an almost correct description of the q dependence of the elastic incoherent scattering function when the number of hydrogen nuclei undergoing the methyl group rotation is considered. It was further evidenced that the fraction of methyl undergoing the methyl group rotation increases with increasing temperature.
KW - Polymers of Intrinsic Microporosity
KW - Neutron scattering
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630297
DO - https://doi.org/10.1016/j.polymer.2025.128358
SN - 1873-2291
VL - 328
SP - 241
PB - Elsevier Ltd.
AN - OPUS4-63029
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Stühler, Merlin R.
A1 - Makki, Hesam
A1 - Silbernagl, Dorothee
A1 - Dimde, Mathias
A1 - Ludwig, Kai
A1 - Tegner, Bengt E.
A1 - Greve, Christopher
A1 - Rausch, Konstantin
A1 - Herzig, Eva M.
A1 - Köhler, Anna
A1 - Plajer, Alex J.
T1 - Flexibility and Dynamicity Enhances and Controls Supramolecular Self-Assembly of Zinc(II) Metallogels
N2 - Supramolecular self-assembly of stacked architectures is typically achieved through hydrogen bonding or π–π interactions between monomers constructed from stable and inert bonds. In contrast, coordinative interactions of early metals promise distinct self-assembly behaviour due to more flexible bonding geometries and a wider range of stabilities and exchange kinetics. In this report we demonstrate that tailoring the flexible coordination sphere of Zinc(II) complexes via subtle ligand modification promotes not only one but also three-dimensional self-assembly both thermodynamically and kinetically into higher-order fibrous morphologies, the latter being elucidated by electron tomography. As a result, coordination chemistry can be translated into both nanoscopic (fibre stiffness) and macroscopic (thermal gel stability) material properties. Utilizing dynamicity enables gelation via subcomponent self-assembly, constructing the supramolecular polymer network simultaneously with the monomer. Furthermore, coordinative dis- and reassembly via metal-ligand exchange reactions involving the first and second coordination spheres allows for control over gelation and emission of the system. Our report links concepts in supramolecular self-assembly and coordination chemistry by leveraging the unique bonding interactions that cannot be achieved for traditional monomers, promising applications in stimuli-responsive optoelectronics.
KW - Nanomaterial
KW - AFM
KW - Organometallic
KW - Gel
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-634221
DO - https://doi.org/10.1002/adfm.202507793
SN - 1616-301X
SP - 1
EP - 10
PB - Wiley-VCH GmbH
CY - Weinheim
AN - OPUS4-63422
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Liu, Yuanbin
A1 - Morrow, Joe D.
A1 - Ertural, Christina
A1 - Fragapane, Natascia L.
A1 - Gardner, John L. A.
A1 - Naik, Aakash A.
A1 - Zhou, Yuxing
A1 - George, Janine
A1 - Deringer, Volker L.
T1 - An automated framework for exploring and learning potential-energy surfaces
N2 - Machine learning has become ubiquitous in materials modelling and now routinely enables large-scale atomistic simulations with quantum-mechanical accuracy. However, developing machine-learned interatomic potentials requires high-quality training data, and the manual generation and curation of such data can be a major bottleneck. Here, we introduce an automated framework for the exploration and fitting of potential-energy surfaces, implemented in an openly available software package that we call (‘automatic potential-landscape explorer’). We discuss design choices, particularly the interoperability with existing software architectures, and the ability for the end user to easily use the computational workflows provided. We show wide-ranging capability demonstrations: for the titanium–oxygen system, SiO2, crystalline and liquid water, as well as phase-change memory materials. More generally, our study illustrates how automation can speed up atomistic machine learning in computational materials science.
KW - Automation
KW - Machine Learning
KW - Machine learning potentials
KW - Amorphous materials
KW - High-throughput
KW - Ab initio
KW - Materials property prediction
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-639882
DO - https://doi.org/10.1038/s41467-025-62510-6
SN - 2041-1723
VL - 16
IS - 1
SP - 1
EP - 12
PB - Springer Science and Business Media LLC
AN - OPUS4-63988
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Amariamir, Sasan
A1 - George, Janine
A1 - Benner, Philipp
T1 - SynCoTrain: a dual classifier PU-learning framework for synthesizability prediction
N2 - Material discovery is a cornerstone of modern science, driving advancements in diverse disciplines from biomedical technology to climate solutions. Predicting synthesizability, a critical factor in realizing novel materials, remains a complex challenge due to the limitations of traditional heuristics and thermodynamic proxies. While stability metrics such as formation energy offer partial insights, they fail to account for kinetic factors and technological constraints that influence synthesis outcomes. These challenges are further compounded by the scarcity of negative data, as failed synthesis attempts are often unpublished or context-specific. We present SynCoTrain, a semi-supervised machine learning model designed to predict the synthesizability of materials. SynCoTrain employs a co-training framework leveraging two complementary graph convolutional neural networks: SchNet and ALIGNN. By iteratively exchanging predictions between classifiers, SynCoTrain mitigates model bias and enhances generalizability. Our approach uses Positive and Unlabeled (PU) learning to address the absence of explicit negative data, iteratively refining predictions through collaborative learning. The model demonstrates robust performance, achieving high recall on internal and leave-out test sets. By focusing on oxide crystals, a well-characterized material family with extensive experimental data, we establish SynCoTrain as a reliable tool for predicting synthesizability while balancing dataset variability and computational efficiency. This work highlights the potential of co-training to advance high-throughput materials discovery and generative research, offering a scalable solution to the challenge of synthesizability prediction.
KW - Synthesizability
KW - Accelerated Materials Design
KW - Materials Acceleration Platforms
KW - Materials Design
KW - Materials Discovery
KW - Co-training
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-637907
DO - https://doi.org/10.1039/D4DD00394B
SN - 2635-098X
VL - 4
IS - 6
SP - 1437
EP - 1448
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-63790
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Zhuang, Yiling
A1 - Haderlein, Stefan B.
A1 - Lutze, Holger V.
A1 - Sun, Chen
A1 - Fink, Friedrich
A1 - Paul, Andrea
A1 - Spahr, Stephanie
T1 - Persulfate activation by biochar for trace organic contaminant removal from urban stormwater
N2 - Persistent and mobile trace organic contaminants (TrOCs) in urban stormwater are difficult to remove through sedimentation- or sorption-based treatment and pose a risk to aquatic ecosystems and drinking water supplies. We demonstrate that the chemical oxidant peroxydisulfate (PDS) can be activated by shrimp shell biochar at pH 7 to form reactive species that selectively react with widespread stormwater contaminants. Of 11 TrOCs tested, oxidative transformation was observed for 1,3-diphenylguanidine, 2-hydroxybenzothiazole, 1H-benzotriazole, 5-methyl-benzotriazole, and diuron during water treatment with biochar and PDS. Laboratory batch experiments conducted with street runoff and a synthetic water showed that the water matrix, containing up to 7.5 mg L-1 dissolved organic carbon and 100 mM chloride, had a minor effect on the formation of reactive species and contaminant transformation. Using a set of scavengers and probe compounds, we provide evidence for singlet oxygen (1O2) as the predominant reactive species in the biochar/PDS system, which is in agreement with the selectivity of the process to oxidize electron-rich organic contaminants. The results of our study inform new strategies for stormwater treatment using heterogeneous oxidation processes for the abatement of persistent and mobile organic contaminants.
KW - Stormwater treatment
KW - Oxidation processes
KW - Pyrogenic carbon
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-637952
DO - https://doi.org/10.1016/j.watres.2025.123921
SN - 0043-1354
VL - 284
SP - 1
EP - 8
PB - Elsevier Ltd.
AN - OPUS4-63795
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Yildirim, Arda
A1 - Haug, T. C. V.
A1 - Fröba, M.
A1 - Huber, P.
A1 - Schönhals, Andreas
T1 - Molecular fluctuations in mixed-metal MOF-74: influence of the metal composition
N2 - A selected series of metal–organic frameworks M-MOF-74 (M = Mg, Co, Ni) and mixed metal MM-MOF-74 (Mg/Co or Mg/Ni) with different compositions of metal atoms have been prepared and further investigated by broadband dielectric spectroscopy (BDS) in a wide temperature range. The dielectric spectra show at least two relaxation processes. Process-A is observed only for the Ni-containing MOFs and is attributed to localized fluctuations of the metal oxide corners. Relaxation processes-B and -C are observed for all prepared MOFs, except that process-B is not observed for Ni-MOF-74. Large-angle fluctuations such as free rotations of the linkers can be excluded due to the structure of MOF-74, but small-angle fluctuations such as torsions are possible. According to numerical simulations carried out for MOF-74, process-B can be attributed to inward and outward fluctuations of the linkers relative to the pore center.
Process-C is related to small-angle rotational fluctuations of the linker together with co-rotations of the metal nodes. The latter interpretation is supported by the dependence of the activation energy of the relaxation rate of process-C on the metal composition of the MOFs, which is discussed in terms of the bond lengths between the metal atoms and the linker which decrease in the sequence Mg, Co and Ni.
KW - Metal Organic Frameworks
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-639378
DO - https://doi.org/10.1039/d5ra05357a
SN - 2046-2069
VL - 15
IS - 35
SP - 29109
EP - 29118
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-63937
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kolmangadi, Mohamed A.
A1 - Raab, A. R.
A1 - Szymoniak, Paulina
A1 - Li, Z.
A1 - Huber, P.
A1 - Laschat, S.
A1 - Schönhals, Andreas
T1 - Molecular mobility and electrical conductivity of amino acid-based (DOPA) ionic liquid crystals in the bulk state and nanoconfinement
N2 - This study explores the molecular mobility, phase behavior, and electrical conductivity of dihydroxyphenylalanine-based ionic liquid crystals (DOPAn, with alkyl side chains n = 12, 14, 16) featuring cyclic guanidiniumchloride headgroups, in both bulk and nanoconfined states. Using broadband dielectric spectroscopy, differential scanning calorimetry, and fast scanning calorimetry, the research uncovers a complex interplay between molecular structure, self-assembly, and molecular mobility. In bulk, DOPAn shows a phase sequence from plastic crystalline to hexagonal columnar and isotropic phases, driven by superdisc formation and columnar organization. Multiple relaxation processes are identified: localized side-chain dynamics (γ-relaxation), ionic headgroup or core motions (α1-relaxation), and cooperative alkyl domain fluctuations (α2-relaxation). Conductivity decreases with increasing side chain length. Under nanoconfinement in anodic aluminum oxide membranes, phase behavior changes: the Colh–Iso transition is suppressed, and a new α3-relaxation appears, linked to dynamics in an adsorbed interfacial layer. DC conductivity drops by up to four orders of magnitude due to confinement effects, altered molecular orientation, and phase transitions—especially the emergence of a nematic-like state in DOPA16. These findings highlight the importance of molecular design, pore geometry, and surface chemistry in tuning ionic liquid crystal properties for advanced applications in nanofluidics, ion transport, and responsive materials.
KW - Ionic Liquid Crystals
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-639657
DO - https://doi.org/10.1039/d5cp02406d
SN - 1463-9084
SP - 1
EP - 17
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-63965
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hülagü, Deniz
A1 - Ermilova, Elena
A1 - Weise, Matthias
A1 - de Préville, Sophie
A1 - Hoffmann, Johannes
A1 - Morán‐Meza, José
A1 - Piquemal, François
A1 - Hertwig, Andreas
T1 - Multimethod Electrical Characterization of Thin Indium Tin Oxide Films: Structuring and Calibration Sample Development for Scanning Probe Microscopy
N2 - Indium tin oxide (ITO), a transparent conductive oxide, is widely used in optoelectronic applications due to its electrical conductivity, optical transparency, and chemical stability. This study employs spectroscopic ellipsometry (SE) to analyze ITO layers, enabling nondestructive determination of film thickness, dielectric functions, and bulk conductivity. Electrical properties derived from SE are compared with those obtained using the four‐point probe method (4PM) to improve metrological tools for nanotechnology applications and optimize deposition process monitoring for better control of film properties. This work also investigates the chemical stability of ITO layers under etching conditions and explores the development of new sheet resistance standards for scanning microwave microscopy (SMM). The results show that ITO resistivity, calculated from fitted SE data, increases with oxygen flow rate up to 5 cm3(STP) min−1. Good agreement is observed between sheet resistance values obtained by SE and 4PM up to 3 cm3(STP) min−1. Additionally, the sheet resistance values of a distinct set of microstructured ITO samples with different ITO layer thicknesses are determined by SMM, which are highly consistent with those obtained by the 4PM.
KW - Ellipsometry
KW - Indium tin oxide (ITO)
KW - Scanning microwave microscopy (SMM)
KW - Sheet resistance calibration standards
KW - ITO wet etching
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-626242
DO - https://doi.org/10.1002/pssa.202400871
SN - 1862-6300
VL - 222
IS - 14
SP - 1
EP - 18
PB - Wiley
CY - Hoboken, New Jersey, USA
AN - OPUS4-62624
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Monroy, José del Refugio
A1 - Deshpande, Tejas
A1 - Schlecht, Joël
A1 - Douglas, Clara
A1 - Stirling, Robbie
A1 - Grabicki, Niklas
A1 - Smales, Glen Jacob
A1 - Kochovski, Zdravko
A1 - Fabozzi, Filippo Giovanni
A1 - Hecht, Stefan
A1 - Feldmann, Sascha
A1 - Dumele, Oliver
T1 - Homochiral versus racemic 2D covalent organic frameworks
N2 - The synthesis of homochiral two-dimensional covalent organic frameworks (2D COFs) from chiral π-conjugated building blocks is challenging, as chiral units often lead to misaligned stacking interactions. In this work, we introduce helical chirality into 2D COFs using configurationally stable enantiopure and racemic [5]helicenes as linkers in the backbone of 2D [5]HeliCOFs as powders and films. Through condensation with 1,3,5-triformylbenzene (TFB) or 1,3,5-triformylphloroglucinol (TFP), our approach enables the efficient formation of a set of homochiral and racemic 2D [5]HeliCOFs. The resulting carbon-based crystalline and porous frameworks exhibit distinct structural features and different properties between homochiral and racemic counterparts. Propagation of helical chirality into the backbone of the crystalline frameworks leads to the observation of advanced chiroptical properties in the far-red visible spectrum, along with a less compact structure compared with the racemic frameworks. Homogeneous thin films of [5]HeliCOFs disclosed photoluminescent properties arising from the controlled growth of highly ordered π-conjugated lattices. The present study offers insight into general chiral framework formation and extends the Liebisch−Wallach rule to 2D COFs.
KW - Chirality
KW - Covalent organic frameworks
KW - Diffraction
KW - Lattices
KW - Thin films
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-633755
DO - https://doi.org/10.1021/jacs.5c01004
SN - 0002-7863
VL - 147
IS - 21
SP - 17750
EP - 17763
PB - American Chemical Society (ACS)
CY - Washington, DC
AN - OPUS4-63375
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Gupta, Kanhaiya
A1 - Poka, Konstantin
A1 - Ulbricht, Alexander
A1 - Waske, Anja
T1 - Identification and authentication of additively manufactured components using their microstructural fingerprint
N2 - In the field of additive manufacturing, the ability to uniquely identify and authenticate parts is crucial for certification, logistics, and anti-counterfeiting efforts. This study introduces a novel methodology that leverages the intrinsic microstructural features of additively manufactured components for their identification, authentication, and traceability. Unlike traditional tagging methods, such as embedding QR codes on the surface or within the volume of parts, this approach requires no alteration to the printing process, as it utilizes naturally occurring microstructural characteristics. The proposed workflow involves the analysis of 3D micro-computed tomography data to identify specific voids that meet predefined identification criteria. This method is demonstrated on a batch of 24 parts manufactured with identical process parameters, proving capable of achieving unambiguous identification and authentication. By establishing a tamper-proof link between the physical part and its digital counterpart, this methodology effectively bridges the physical and digital realms. This not only enhances the traceability of additively manufactured parts but also provides a robust tool for integrating digital materials, parts databases, and product passports with their physical counterparts.
KW - Authentication
KW - Additive manufacturing
KW - X-ray Computed Tomography
KW - Digital fingerprint
KW - Unique identification
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630356
DO - https://doi.org/10.1016/j.matdes.2025.113986
SN - 1873-4197
VL - 254
SP - 1
EP - 12
PB - Elsevier Ltd.
CY - Amsterdam
AN - OPUS4-63035
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Nikitin, D.
A1 - Biliak, K.
A1 - Protsak, M.
A1 - Adejube, B.
A1 - Ali-Ogly, S.
A1 - Škorvanková, K.
A1 - Červenková, V.
A1 - Katuta, R.
A1 - Tosco, M.
A1 - Hanuš, J.
A1 - Černochová, Z.
A1 - Černoch, P.
A1 - Štěpánek, P.
A1 - Boiko, O.
A1 - Szymoniak, Paulina
A1 - Schönhals, Andreas
A1 - Faupel, F.
A1 - Biedermann, H.
A1 - Vahl, A.
A1 - Choukourov, A.
T1 - Unveiling the Fundamental Principles of Reconfigurable Resistance States in Silver/Poly(ethylene glycol) Nanofluids
N2 - Developing novel memristive systems aims to implement key principles of biological neuron assemblies – plasticity, adaptivity, and self-organization – into artificial devices for parallel, energy-efficient computing. Solid-state memristive devices, such as crossbar arrays and percolated nanoparticle (NP) networks, already demonstrate these properties. However, closer similarity to neural networks is expected from liquid-state systems, including polymer melts, which remain largely unexplored. Here, the resistive switching in silver/poly(ethylene glycol) (Ag/PEG) nanofluids, prepared by depositing gas-aggregated Ag NPs into PEGs of varying molecular mass, is investigated.
These systems form long-range conductive NP bridges with reconfigurable resistance states in response to an electric field. The zeta-potential of Ag NPs and molecular mobility of PEG determine the prevalence of low resistance (ohmic) state, high resistance states (poor conductance) or intermediate transition states governed by space-charge-limited conduction or electron tunneling. The occurrence of these states is given by the interparticle gaps, which are determined by the conformation of PEG molecules adsorbed on the NPs. It is presented, for the first time, an equivalent circuit model for the Ag/PEG system. These findings pave the way to adopt polymer melts as matrices for neuromorphic engineering and bio-inspired electronics.
KW - Nanofluids
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-635351
DO - https://doi.org/10.1002/advs.202505103
VL - 12
SP - 1
EP - 14
PB - Wiley
AN - OPUS4-63535
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hörmann, Anja F.
A1 - Simon, Miriam
A1 - Brückner, Christoph
A1 - Rogers, Sarah E.
A1 - Porcar, Lionel
A1 - Hoffmann, Ingo
A1 - Gradzielski, Michael
T1 - Line tension controls the spontaneous formation of vesicles
N2 - Mixtures of the zwitterionic surfactant TDMAO and the anionic surfactant LiPFOS spontaneously self-assemble into well defined vesicles. The size of these vesicles is determined by the ratio of bending rigidity and line tension. By partially charging TDMAO, and thereby moving more to a catanionic system, the size of these vesicles can be controlled. Using stopped flow small angle neutron scattering we monitor the kinetics of vesicle formation and obtain their final size. Neutron spin echo spectroscopy allows for an independent measurement of the vesicle’s bending rigidity. Combining this bending rigidity with the radius of newly formed vesicles, which is determined by the ratio of bending rigidity and line tension, we can determine the line tension. We find that it is the line tension that controls the trend in size of the vesicles. In summary, this means that here one has a surfactant mixture that delivers well-defined vesicles, whose size is controlled by the electrostatic interactions of the head groups.
KW - Self-assembly
KW - Small unilamellar vesicles
KW - Small-angle neutron scattering
KW - Line tension
KW - Neutron spin-echo spectroscopy
KW - Stopped-flow
KW - Bending rigidity
KW - Surfactant mixture
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-646964
DO - https://doi.org/10.1039/D5SM00600G
SN - 1744-683X
VL - 21
IS - 43
SP - 8360
EP - 8367
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-64696
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Voss, Heike
A1 - Zahedi-Azad, Setareh
A1 - Ernst, Owen C.
A1 - Lucaßen, Jan
A1 - Mann, Guido
A1 - Bonse, Jörn
A1 - Boeck, Torsten
A1 - Martin, Jens
A1 - Schmid, Martina
A1 - Krüger, Jörg
T1 - Chemical vapor deposition of indium precursors for solar microabsorbers using continuous laser radiation
BT - A, Materials science & processing
N2 - Localized deposition of indium on an amorphous glass surface covered with a thin molybdenum layer is demonstrated utilizing laser-assisted chemical vapor deposition. A continuous-wave laser causes a temperature rise on the molybdenum layer resulting in the selective aggregation of liquid and ultimately crystalline structures of indium. The formation sites of the indium are determined by the decomposition of gaseous trimethylindium. The deposited indium islands can serve as precursors and could be further processed into compound semiconductors like CuInSe2 for micro-concentrator solar cells. The experimental investigations were supported by theoretical simulations of the laser heating process to calculate the local temperature distribution on the surface of the molybdenum-covered glass substrate.
KW - Laser-assisted Chemical Vapor Deposition
KW - CW Laser
KW - Indium Islands
KW - Micro-concentrator Solar Cell
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-641069
DO - https://doi.org/10.1007/s00339-025-08895-z
SN - 0947-8396
VL - 131
SP - 1
EP - 10
PB - Springer
CY - Berlin ; Heidelberg [u.a.]
AN - OPUS4-64106
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Cope, Elana J.
A1 - Bustamante, Joana
A1 - Johnson, Zöe M.
A1 - Lancaster, Alicia
A1 - Gurunathan, Ramya
A1 - George, Janine
A1 - Agne, Matthias T.
T1 - Heat capacity estimation of complex materials for energy technologies
N2 - The control of heat in energy materials is one of the greatest current engineering challenges. Accurate estimations of heat capacity are key in creating and using materials safely and efficiently. Current models for heat capacity are often limited due to crude estimations of the phonon density of states, which is a key component of the thermodynamic definition of heat capacity. Utilization of a more detailed phonon density of states, which can easily be obtained from machine-learned algorithms, combined with dilation and electronic contributions, yields heat capacity estimations that are 29% better than the widely utilized Debye model and are comparable to state-of-the-art quantum mechanical calculations. The framework and necessary tools for heat capacity estimations demonstrated herein can be built into more detailed models and analyses, such as high-throughput characterization, transport models, or other thermodynamic assessments. Consequently, the so-called vibrational + dilation + electronic (VDE) model of heat capacity developed in this work better enables the informed design of next-generation devices.
KW - Materials Design
KW - Heat Capacity
KW - Machine learning potentials
KW - Thermal Management
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-645711
DO - https://doi.org/10.1016/j.joule.2025.102054
SN - 2542-4351
VL - 9
IS - 8
SP - 1
EP - 12
PB - Elsevier Inc.
AN - OPUS4-64571
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -