Ingenieurwissenschaften und zugeordnete Tätigkeiten
Filtern
Erscheinungsjahr
- 2022 (88) (entfernen)
Dokumenttyp
- Zeitschriftenartikel (53)
- Vortrag (21)
- Posterpräsentation (12)
- Sonstiges (1)
- Forschungsdatensatz (1)
Sprache
- Englisch (88)
Schlagworte
- Mechanochemistry (26)
- Nanoparticles (8)
- MALDI-TOF MS (6)
- Polylactide (6)
- Amorphous phases (5)
- In situ (5)
- In situ real-time monitoring (5)
- Struvite (5)
- Biobased polymers (4)
- Phosphates (4)
- Polymorphism (4)
- XAS (4)
- Affinity chromatography (3)
- Anhydrite (3)
- Antibodies (3)
- Automated synthesis (3)
- Calcium sulfate (3)
- Catalysis (3)
- Cocrystal (3)
- Crystallization (3)
- Flexible crystals (3)
- Green chemistry (3)
- MOF (3)
- Mesoporosity (3)
- Metal-organic-frameworks (3)
- Polyglycerol (3)
- Transition metal (3)
- Adsorption (2)
- Cocrystals (2)
- Core-shell (2)
- Crystals (2)
- Cyclization (2)
- Element-specific spectroscopy (2)
- Energetic materials (2)
- Glutaraldehyde (2)
- Gypsum (2)
- High-entropy alloys (2)
- Kinetics (2)
- Lignin (2)
- MALDI TOF MS (2)
- Magnetism (2)
- Materials (2)
- Mesocrystals (2)
- Phenolic compounds (2)
- Polymers (2)
- Purification (2)
- Reductive amination (2)
- Reverse Monte Carlo (RMC) (2)
- SAXS (2)
- Sapphire (2)
- SnO2 (2)
- TRIS (2)
- Time resolved (2)
- Transition metals (2)
- Waveguide (2)
- X-ray absorption spectroscopy (2)
- XRD (2)
- 1,2,3-triazole (1)
- Ab initio simulation (1)
- Affinity extraction (1)
- Affinity support (1)
- Aluminum oxide (1)
- Amino acid analysis (1)
- Amphiphilicity (1)
- Antibody purification (1)
- Anticancer (1)
- Aqueous synthesis (1)
- Aromatic amino acid analysis AAAA (1)
- Aromatic amino acid analysis aaaa (1)
- Aromatic pollutants (1)
- BSA (1)
- Bassanite (1)
- Bifunctionality (1)
- Bimetallic frameworks (1)
- Bioconjugation (1)
- Bioseparation (1)
- Bismuth (1)
- Bismuth Ferrite (1)
- Bovine serum albumin (1)
- Carrier (1)
- Chemputer (1)
- Chromatography (HIC) (1)
- Clerodin (1)
- Cobalt (1)
- Corundum (1)
- Crystal (1)
- Crystal Engeneering (1)
- Crystal Engineering (1)
- Crystal growth (1)
- Crystalinity (1)
- Cu catalysts (1)
- Cycloaddition (1)
- DFT (1)
- Dendrimer (1)
- Depollution (1)
- Diffraction (1)
- Dipsersive XAS (1)
- Downstream processing (1)
- ESEM (1)
- EXAFS (1)
- Electrical properties (1)
- Electrochemical CO2 conversion (1)
- Electrode materials (1)
- Electrodes (1)
- Evaporation (1)
- Extended X-ray absorption fine structure (EXAFS) (1)
- Extended X-ray absorption fine structure (EXAFS), (1)
- Ferroelectric (1)
- Filter (1)
- Flexible waveguide (1)
- Fluorescence (1)
- Fluorinated MOFs (1)
- Functionality type distribution (1)
- Gandolfi method (1)
- H3PO3 (1)
- H3PO4 life cycle (1)
- Halide Perovskites (1)
- Halogen bond interaction (1)
- High entropy alloys (1)
- High-density polyethylene (1)
- High-temperature fuel cells (1)
- Human plasma (1)
- Hydrophobic interaction (1)
- Hyperbranched polymer (1)
- Igg (1)
- Immunoglobulins (1)
- Immunoprecipitation (1)
- In situ EXAFS (1)
- In situ PXRD (1)
- In situ SAXS/WAXS (1)
- In situ X-ray diffraction (1)
- In situ coupling (1)
- In situ diffraction (1)
- In situ studies (1)
- In-situ analysis (1)
- Insulators (1)
- Isosorbide (1)
- Kinetics from experiments (1)
- Lactide (1)
- Lacunary Keggin ion (1)
- Lignosulfonate (1)
- Linker (1)
- Liquid chromatography (1)
- MALDI (1)
- MAPbI3 perovskites (1)
- Mass spectrometry (1)
- Material synthesis (1)
- Mechanical properties (1)
- Mechanical response (1)
- Mechanochemictry (1)
- Mechanophotonics (1)
- Mesocrystal (1)
- Micromanipulation (1)
- Minerals (1)
- Mixed-ligand MOFs (1)
- Modification (1)
- Molar mass distribution (1)
- Molecular mass distribution (1)
- Multicomponent (1)
- N-Chlorination (1)
- NMR (1)
- Nickel (1)
- Nitric acid (1)
- Nobel-metal free electrocatalysis (1)
- Non-classical crystallization (1)
- Non-classical crystallization theory (1)
- Nonlinear optics (1)
- Nonspecific binding (NSB) (1)
- OER (1)
- Optical waveguides (1)
- Organic compounds (1)
- Organic-inorganic adsorbents (1)
- Pentafluoropyridine (1)
- Periodate oxidation (1)
- Phase transition (1)
- Phosphate (1)
- Phosphonic acids (1)
- Phosphorous recovery (1)
- Photocatalysis (1)
- Piezoresponse (1)
- Polarization (1)
- Poly(ether-phosphoramide)s sulfides (1)
- Poly(ether-sulfone) (1)
- Polycondensation (1)
- Polymer film (1)
- Polymerization (1)
- Polymorph (1)
- Polymorphs (1)
- Polyoxometalates (1)
- Postsynthetic modification (1)
- Precipitation (1)
- Protein (1)
- Protein a (1)
- Protein hydrolysis (1)
- Protein immobilization (1)
- Protein quantification (1)
- Proton conductivity (1)
- Quantum mechanics (1)
- Reactions (1)
- Reversible adsorption. (1)
- Ring opening polymerization (1)
- Ring-expansion polymerization (1)
- Ring-opening polymerization (1)
- SDS-PAGE (1)
- Scattering (1)
- Self-assembled monolayer (SAM) (1)
- Self-assembled monolayers (SAM) (1)
- Self-assembly (1)
- Semi-Interpenetrating Network (1)
- Semi-interpenetrating networks (1)
- Separability assumption (1)
- Sequential spectroscopic data (1)
- Short range order (1)
- Silica gel modification (1)
- Sillver (1)
- Silver (1)
- Single crystal (1)
- Size-exclusion chromatography (SEC) (1)
- Solid phase (1)
- Solid state NMR (1)
- Solid-phase extraction (SPE) (1)
- Structure-mechanical property correlation (1)
- Stuccos (1)
- Sulfates (1)
- Sustainable chemisry (1)
- Synchrotron radiation (1)
- Synthesis (1)
- TEM (1)
- Thermal expansion (1)
- Time-resolved (1)
- Tin catalysts (1)
- Topas (1)
- Transesterification (1)
- Two-dimensional chromatography (2D-LC) (1)
- Two-dimensional liquid chromatography (2D-LC) (1)
- Tyrosine (1)
- UV radiation (1)
- Up-cycling (1)
- Variable temperature (1)
- Vickers hardness (1)
- X-ray absorption near edge structure (XANES) (1)
- X-ray diffraction (1)
- X-ray magnetic circular dichroism (XMCD), (1)
- XANES (1)
- ZIF-8 (1)
- Zinc catalyst (1)
- ring-expansion polymerization (1)
- Δμ XANES (1)
Organisationseinheit der BAM
- 6.3 Strukturanalytik (88) (entfernen)
Paper des Monats
- ja (1)
Using solid catalysts in disulfide-based dynamic combinatorial solution- and mechano-chemistry
(2022)
We here show for the first time that solid amines can act as catalysts for disulfide-based dynamic combinatorial chemistry by ball mill grinding. The mechanochemical Equilibrium for the two disulfide reactions studied is reached within one to three hours using ten different amine catalysts. This contrasts with the weeks to months to achieve solution equilibrium for most solid amine catalysts at 2%M at 2mM concentration in a suitable solvent. The final mechanochemical equilibrium is independent of the catalyst used, but varies with other ball mill grinding factors such as the presence of traces of solvent. The different efficiencies of the amines tested are discussed.
Unintended Rate Enhancement in Mechanochemical Kinetics by Using Poly(methyl methacrylate) Jars
(2022)
Time-resolved in situ (TRIS) X-ray diffraction has changed how mechanochemical transformations are studied but requires the use of X-ray transparent jars often made from poly(methyl methacrylate) (PMMA). However, using PMMA jars can alter the apparent kinetics of mechanochemical polymorphism by an order of magnitude, questioning the interpretability of established TRIS methods. Our results suggest that rate enhancement in PMMA jars may not be dominated by chemical effects of the polymer, but rather a result of different equilibrium temperatures within the jar. These features must be better understood before control over mechanochemical reactions can be achieved.
Trash to treasure: recovery of transition metal phosphates for (electro-)catalytical applications
(2022)
Wastewaters containing high concentrations of NH4+, PO43- and transition metals are environmentally harmful and toxic pollutants. At the same time phosphorous and transition metals constitute valuable resources. Here, we report the synthesis routes for Co- and Ni-struvites (NH4MPO4∙6H2O, M = Ni2+, Co2+) out of aqueous solutions resembling synthetic/industrial waste water compositions, and allowing for P, ammonia and metal co-precipitation. Furthermore, the as-obtained struvites were further up-cycled. When heated, these transition metal phosphates (TMPs) demonstrate significant changes in the degree of crystallinity/coordination environment involving a high amount of amorphous phases and importantly develop mesoporosity (Figure 1). In this regard, amorphous and mesoporous TMPs are known to be highly promising (electro-)catalysts.
Amorphous phases do not represent a simple “disordered” crystal but more a complex system with a broad range of compositions and physicochemical properties, which remain mostly unknown. Consequently, we investigated the recrystallization and amorphization process during thermal treatment and a resolved the complex amorphous/crystalline structures (Figure 2). As a proof-of-principle for their applicational use, the as-obtained TMPs demonstrate significant proton conductivity properties similar to apatite-like structures from room to high temperatures (>800°C).
Hence, we have developed a promising recycling route in which environmental harmful contaminants like PO43-, NH4+ and 3d metals would be extracted out of waste waters in the form of precursor raw materials. These raw materials can be then further up-cycled through a simple thermal treatment for their specific application in electrocatalysis.
Metal nanoparticles have a substantial impact across diferent felds of science, such as photochemistry, energy conversion, and medicine. Among the commonly used nanoparticles, silver nanoparticles are of special interest due to their antibacterial properties and applications in sensing and catalysis. However, many of the methods used to synthesize silver nanoparticles often do not result in well-defned products, the main obstacles being high polydispersity or a lack of particle size tunability. We describe an automated approach to on-demand synthesis of adjustable particles with mean radii of 3 and 5 nm using the polyol route. The polyol process is a promising route for silver nanoparticles e.g., to be used as reference materials. We characterised the as-synthesized nanoparticles using small-angle X-ray scattering, dynamic light scattering and further methods, showing that automated synthesis can yield colloids with reproducible and tuneable properties.
n situ monitoring of mechanochemical reactions between dicyandiamide (DCD) and CuX2 salts (X = Cl−, NO3−), for the preparation of compounds of agrochemical interest, showed the appearance of a number of phases. It is demonstrated that milling conditions, such as the amount of water added in wet grinding and/or the milling frequency, may affect the course of the mechanochemical reactions, and drive the reaction towards the formation of different products. It has been possible to discover by in situ monitored experiments two novel crystalline forms, namely the neutral complexes [Cu(DCD)2(OH2)2(NO3)2] (2) and [Cu(DCD)2(OH2)Cl2]·H2O (4), in addition to the previously known molecular salt [Cu(DCD)2(OH2)2][NO3]2·2H2O (1, DIVWAG) and neutral complex [Cu(DCD)2(OH2)Cl2] (3, AQCYCU), for which no synthesis conditions were available. Compounds 2 and 4 were fully characterized via a combination of solid-state techniques, including X-ray diffraction, Raman spectroscopy and TGA.
Mechanochemical transformations offer environmentally benign synthesis routes, whilst enhancing both the speed and selec-tivity of reactions. In this light, mechanochemistry promises to trans-form the way in which chemistry is done in both academia and indus-try but is greatly hindered by a current lack in mechanistic understand-ing. The continued development and use of time-resolved in situ(TRIS) approaches to monitor mechanochemical reactions provides a new dimension to elucidatethese fascinating transformations. We here discuss recent trends in method development that have pushed the boundaries of mechanochemical research. New features of mech-anochemical reactions obtained by TRIS techniques are subse-quently discussed, shedding light on how different TRISapproaches have beenused. Emphasis is placed on the strength of combining complementary techniques. Finally, we outline our views for the po-tential of TRIS methods in mechanochemical research, towards es-tablishing a new, environmentally benign paradigm in the chemical sciences
Mechanochemical reactions promise a new direction for environmentally benign preparation of materials, and has been dubbed by IUPAC as one of the 10 chemical innovations that will change our world. Despite this significant promise, very little is known about the mechanisms that drive mechanochemical transformations, posing significant barriers to realizing their full potential. To this end, there is growing need to follow mechanochemical reactions in situ and in real time. We here describe advances in the development and application of XAS methods to monitor material synthesis in real time under mechanochemical conditions. We demonstrate the generality of our approaches by describing mechanochemical syntheses of materials by both vibratory ball milling and by Resonant Acoustic Mixing (RAM), where a time resolution of 1 second is for a whole XAS spectrum was achieved. Moreover, we describe how spectroscopic methods can be coupled to diffraction-based approaches, thereby providing new dimensions in understanding mechanochemical synthesis.
Mechanochemical reactions promise a new direction for environmentally benign preparation of materials, and has been dubbed by IUPAC as one of the 10 chemical innovations that will change our world. Despite this significant promise, very little is known about the mechanisms that drive mechanochemical transformations, posing significant barriers to realizing their full potential. To this end, there is growing need to follow mechanochemical reactions in situ and in real time. We here describe advances in the development and application of XAS methods to monitor material synthesis in real time under mechanochemical conditions. We demonstrate the generality of our approaches by describing mechanochemical syntheses of materials by both vibratory ball milling and by Resonant Acoustic Mixing (RAM), where a time resolution of 1 second is for a whole XAS spectrum was achieved. Moreover, we describe how spectroscopic methods can be coupled to diffraction-based approaches, thereby providing new dimensions in understanding mechanochemical synthesis.
The polycondensations of adipic acid and 1,10-decanediol catalyzed by toluene sulfonic acid (TSA) were reinvestigated using MALDI TOF mass spectrometry and NMR spectroscopy. Unexpected reactions of TSA were detected along with incomplete conversion of the monomers. Furthermore, transesterification reactions of end-capped poly(1,10-decanediol adipate) and end-capped poly(ε-caprolactone) catalyzed by TSA were studied. Despite the quite different (ionic) reaction mechanisms, it was found that for polycondensations performed in bulk intermolecular transesterification is more efficient than the intramolecular “back-biting”; this scenario was not considered in the Jacobson–Stockmayer theory of reversible polycondensations.
These results also confirm that the Jacobson–Stockmayer explanation of reversible polycondensations solely on the basis of ring chain equilibration is not only devoid of any experimental evidence, but also in contradiction to the results elaborated in this work.
Mechanochemical reactions are driven by the direct absorption of mechanical energy by a solid (often crystalline) material. Understanding how this energy is absorbed and ultimately causes a chemical transformation is essential for understanding the elementary stages of mechanochemical transformations. Using as a model system the energetic material LiN3 we here consider how vibrational energy flows through the crystal structure. By considering the compression response of the crystalline material we identify the partitioning of energy into an initial vibrational excitation. Subsequent energy flow is based on concepts of phonon–phonon scattering, which we calculate within a quasi-equilibrium model facilitated by phonon scattering data obtained from Density Functional Theory (DFT). Using this model we demonstrate how the moments (picoseconds) immediately following mechanical impact lead to significant thermal excitation of crystalline LiN3, sufficient to drive marked changes in its electronic structure and hence chemical reactivity. This work paves the way towards an ab initio approach to studying elementary processes in mechanochemical reactions involving crystalline solids.