Filtern
Erscheinungsjahr
Dokumenttyp
- Zeitschriftenartikel (180)
- Vortrag (39)
- Beitrag zu einem Tagungsband (16)
- Posterpräsentation (13)
- Beitrag zu einem Sammelband (9)
- Buchkapitel (2)
Schlagworte
- MALDI-TOF MS (63)
- Polylactide (45)
- Cyclization (27)
- MALDI (21)
- Ring-opening polymerization (17)
- Polycondensation (15)
- MALDI TOF MS (11)
- Mass spectrometry (9)
- Pollen (8)
- Polymerization (8)
- Transesterification (8)
- Crystallization (7)
- Polymers (7)
- Ring-expansion polymerization (7)
- Catalyst (6)
- Crystalinity (6)
- Ionization (6)
- Polymere (6)
- Catalysts (5)
- Isosorbide (5)
- Lactide (5)
- Polyester (5)
- MALDI Massenspektrometrie (4)
- MALDI-TOF mass spectrometry (4)
- Polyesters (4)
- Polyglycolide (4)
- Polylactides (4)
- Ring opening polymerization (4)
- Biobased polymers (3)
- Bismuth (3)
- Cyclic (3)
- ICP-MS (3)
- Imaging (3)
- Liquid chromatography (3)
- Multivariate statistics (3)
- Polymer (3)
- Polymerisation (3)
- Polyurethane (3)
- ROPPOC (3)
- SEC (3)
- Silver nanoparticles (3)
- Small-angle X-ray scattering (3)
- Adsorption (2)
- Amphiphiles (2)
- Annealing (2)
- Biodegradable (2)
- Blends (2)
- Block copolymers (2)
- Catechol (2)
- Chromatographie (2)
- Chromatography (2)
- Conductive carbon tape (2)
- Coupling methods (2)
- Crosslinking (2)
- Crystals (2)
- Cyclopolymerization (2)
- Dispersity (2)
- ESI (2)
- Electrospray ionization (2)
- Epsilon-caprolactone (2)
- FTIR (2)
- Field-flow fractionation (2)
- Isotope dilution analysis (2)
- Kopplung (2)
- Liquid adsorption chromatography (2)
- MALDI mass spectrometry (2)
- MALDI-TOF-MS (2)
- MS/MS (2)
- Macrocycles (2)
- Massenspektrometrie (2)
- Matrix-assisted laser desorption/ionization (2)
- Plasma modification (2)
- Polystyrene (2)
- Polyurethanes (2)
- Principal component analysis (2)
- Reversible addition fragmentation chain transfer (RAFT) (2)
- Ring-opening Polymerization (2)
- SAXS (2)
- Sample preparation (2)
- Sample pretreatment (2)
- Synthesis (2)
- TPU (2)
- Thermal degradation (2)
- Tin acetates (2)
- Tin catalysts (2)
- 2-oxazoline (1)
- A4F (1)
- AET (1)
- AFM (1)
- Abbauverhalten (1)
- Adhesion promoting interlayers (1)
- Adhesion promotion (1)
- Alternating co-poly(ether pyridine)s (1)
- Amphiphilic polymers (1)
- Application (1)
- Aromatic organic compounds, (1)
- Aromatic pollutants (1)
- Artificial weathering (1)
- Aryl iodides (1)
- Asymmetric flow filed-flow fractionation (1)
- Asymmetrical flow field flow fractionation (AF4) (1)
- Attenuated total reflectance-Fourier transorm infrared spectroscopy (1)
- Bewitterung (1)
- Bioabbaubare Polymere (1)
- Biobased (1)
- Biodegradability (1)
- Biodegradable polyesters (1)
- Biopolymers (1)
- Biosourced isosorbide (1)
- Blockcopolymer (1)
- CRM (1)
- Caco-2 cells (1)
- Caesium (1)
- Capillary electrophoresis (1)
- Capillary electrophoresis (CE) (1)
- Carbon capture (1)
- Carbon fiberepoxy resin laminates (1)
- Carboxyl group (1)
- Catalytic ability (1)
- Cationic ring opening polymerization (1)
- Cationization (1)
- Chain scission (1)
- Chemical conversion of functional groups (1)
- Chemical reduction of functional groups (1)
- Classification (1)
- Click chemistry (1)
- Climate change (1)
- Conjugated oligomers (1)
- Controlled radical polymerization (1)
- Conversion (1)
- Copolyester (1)
- Copolymer composition (1)
- Copolymer sequence (1)
- Copolymeranalytik (1)
- Copolymerization (1)
- Copolymers (1)
- Cotton effect (1)
- Coupling (1)
- Coupling techniques (1)
- Crystallinity (1)
- Cyclics (1)
- Cyclisation (1)
- Cycloaddition (1)
- Cycloparaphenylenes (1)
- DCTB (1)
- Degradation (1)
- Dendrimers (1)
- Dendrons (1)
- Depollution (1)
- Desorption (1)
- Dried droplet (1)
- Droplet (1)
- Dynamic light scattering (1)
- ESI-Massenspektrometrie (1)
- ESI-TOF MS (1)
- Electron paramagnetic resonance study (1)
- Electrospray (1)
- Electrospray ionization (ESI) (1)
- Epsilon-Caprolactone (1)
- Epsilon-caprolactone (e-CL) (1)
- Equilibration (1)
- Europium (1)
- Feuchte (1)
- Field flow fractionation (1)
- Foldamers (1)
- Fractionation of polymers (1)
- Fragmentierung (1)
- Friction (1)
- Ft-IR (1)
- Functionalized graphene nanoribbons (1)
- Fundamentals (1)
- Glycodendrimers (1)
- Glycolide (1)
- Gradient chromatography (1)
- Gradient elution (1)
- Gradient elution liquid chromatography (GELC) (1)
- Graphene monomers (1)
- Graphene nanoribbons (1)
- Graphene wires (1)
- Green chemistry (1)
- HPLC (1)
- Hafnium (1)
- Heavy metals (1)
- Hexabenzocoronene (1)
- Hierarchical cluster analysis (1)
- Hierarchical self-assembly (1)
- High performance liquid chromatography (1)
- Host–guest systems (1)
- Humidity (1)
- Hybrid nanoparticles (1)
- Hydrolytic degradation (1)
- Hyperbranched polyesters (1)
- Hyphenated techniques (1)
- Imaging MS (1)
- Imaging techniques (1)
- In situ EXAFS (1)
- In situ SAXS/WAXS (1)
- In vitro digestion (1)
- Inductively coupled plasma-mass spectrometry (1)
- Inlet ionization (1)
- Intrinsic viscosity (1)
- Ion mobility (1)
- Ionization mass spectrometry (1)
- Iron oxide nanoparticles (1)
- Irreversible polycondensation (1)
- Isophthalic acid (1)
- Jacobsen-Stockmayer theory (1)
- Klassifizierung (1)
- Kopplungsmethoden (1)
- L-lactide (1)
- LC-MS coupling (1)
- Lactides (1)
- Lacunary Keggin ion (1)
- Lanthanide ions (1)
- Laser-induced redox reactions (1)
- Layer topography (1)
- Lead ions (1)
- Light scattering (LS) (1)
- Linear (1)
- Liquid adsorption chromatography at critical conditions (1)
- Liquid chromatography at critical conditions (1)
- Liquid chromatography under critical conditions (LCCC) (1)
- Lubricant (1)
- MALDI Imaging (1)
- MALDI Imaging MS (1)
- MALDI TOF Massenspektrometrie (1)
- MALDI TOF mass spectrometry (1)
- MALDI-TOF (1)
- MALDI-TOF MS/MS (1)
- MALDI-TOF Mass Spectrometry (1)
- MALDI-TOF Massenspektrometrie (1)
- MALDI-ToF MS (1)
- MOF (1)
- Mass Spectrometry (1)
- Mass spectrometry imaging (1)
- Materials Chemistry (1)
- Matrices (1)
- Matrix segregation (1)
- Matrix-assisted ionization ion mobility spectrometry mass spectrometry (1)
- Matrix-assisted laser desorption (1)
- Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS) (1)
- Matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry (1)
- Mechanism (1)
- Mechanism of polymerization (1)
- Mega-dalton (1)
- Metal ion complexation (1)
- Metal ion-intradendrimer complexes (1)
- Metal triflates (1)
- Metal-polymer interactions (1)
- Metal-polymer systems (1)
- Micro manufacturing (1)
- Microwave (1)
- Moisture (1)
- Molar mass determination (1)
- Molar mass distribution (1)
- Molecular masses (1)
- Molecular recognition (1)
- Morphology (1)
- Multicyclic polymers (1)
- Multiphysics simulations (1)
- Multivariate Analyse (1)
- Multivariate Statistics (1)
- Multivariate analyses (1)
- N-vinyl pyrrolidone (1)
- Nanolithography (1)
- Nanoparticle (1)
- Nanoparticles (1)
- Nanoparticles separation asymetrical flow field flow fractionation (1)
- Nanoparticles with same nominal diameter (1)
- Networks (1)
- Nässe (1)
- Oligoazobenzene (1)
- Oligospiroketals (1)
- On-surface polymerization (1)
- Organic Chemistry (1)
- Oxygen low-pressure plasma treatment of polymers (1)
- PCA (1)
- PET (1)
- Partial least square discriminant analysis (PLS-DA) (1)
- Peel strength (1)
- Pentafluoropyridine (1)
- Phenolic acid (1)
- Phenolic compounds (1)
- Phenyleneethynylenes (1)
- Phosphonate esters (1)
- Photoligation (1)
- Photooxidation (1)
- Photoswitchable (1)
- Plasma (1)
- Plasma polymers with functional groups (1)
- Pollen grains (1)
- Pollenkörner (1)
- Poly(ether-phosphoramide)s sulfides (1)
- Poly(ethylene glycol) (1)
- Poly(ethylene terephthalate) (1)
- Poly(lactide) (1)
- Polyaddition (1)
- Polycaprolactone (1)
- Polycarbonate-co-dimethylsiloxane copolymer (1)
- Polycondensations (1)
- Polyelectrolytes (1)
- Polyethylene (1)
- Polyethylene oxide (1)
- Polyforamidine (1)
- Polykondensation (1)
- Polylaktid (1)
- Polylaktide (1)
- Polymer MALDI (1)
- Polymer blends (1)
- Polymer chromatography (1)
- Polymer film (1)
- Polymer mass spectrometry (1)
- Polymer reference materials (1)
- Polymerization mechanisms (1)
- Polymers and Plastics (1)
- Polyoxometalates (1)
- Polypropylene (1)
- Polysarcosine (1)
- Polyurethan (1)
- Principal component analysis (PCA) (1)
- Quantification (1)
- ROMP (1)
- Raman (1)
- Renewable resources (1)
- Reversible addition/fragmentation chain transfer (RAFT) (1)
- Ring opening polymerization (ROP) (1)
- Ring-opening Polymerisation (1)
- Ring-opening polymerizations (1)
- Salicylate (1)
- Sample loss (1)
- Self-assembly (1)
- Semi-interpenetrating networks (1)
- Silica gel modification (1)
- Size exclusion chromatography (1)
- Size exclusion chromatography (SEC) (1)
- Size-exclusion chromatography (1)
- Sn catalysts (1)
- Soft ionization mass spectrometry (ESI, MALDI) (1)
- Software (1)
- Solvent-free (1)
- Sonoga (1)
- Sorption isotherm (1)
- Sorption mechanism (1)
- Spacers (1)
- Speciation (1)
- Spirocyclic (1)
- Stereocomplex (1)
- Succinic acid (1)
- Sulfobetaines (1)
- Supramolecular chemistry (1)
- Surface analysis (1)
- Surface coating (1)
- Tandem MS (1)
- Target plate material (1)
- Telechelic polyesters (1)
- Thermo-desorption (1)
- Thermochemistry (1)
- Thin polymer layers (1)
- Time of flight (1)
- Tin(II)octanoate (1)
- Toxicity (1)
- Toxicology (1)
- Triazenes (1)
- Two-dimensional off-line coupling (1)
- Two-dimensional-liquid chromatography (2D-LC) (1)
- UPLC (1)
- UV (1)
- UV degradation (1)
- UV radiation (1)
- Ultraschallfalle (1)
- Universal calibration (1)
- Vacuum ionization (1)
- WMRIF (1)
- Water-soluble polymers (1)
- X-ray photoelectron spectroscopy (1)
- Zinc catalyst (1)
- Zyklen (1)
- a2 + b3 polycondensation (1)
- cyclization (1)
- dispersity (1)
- mass spectra (1)
- mass spectrometry (1)
- polycondensation (1)
- polyesters (1)
- polyionic liquids (1)
- r.f. pulsed plasma (1)
- reversible addition fragmentation chain transfer (RAFT) polymerization (1)
- ring-expansion polymerization (1)
- surface modification (1)
Organisationseinheit der BAM
- 6 Materialchemie (88)
- 6.3 Strukturanalytik (88)
- 1 Analytische Chemie; Referenzmaterialien (5)
- 1.2 Biophotonik (2)
- 1.7 Organische Spuren- und Lebensmittelanalytik (2)
- 6.6 Physik und chemische Analytik der Polymere (2)
- 7 Bauwerkssicherheit (2)
- 7.5 Technische Eigenschaften von Polymerwerkstoffen (2)
- 1.0 Abteilungsleitung und andere (1)
- 1.3 Instrumentelle Analytik (1)
Eingeladener Vortrag
- nein (39)
SnOct 2-Catalyzed Syntheses of Cyclic Poly (l-lactide) s with Catechol as Low-Toxic Co-catalyst
(2019)
Polymerizations of l-lactide in bulk at 160 or 180 °C were performed with 1/1 mixtures of catechol (CA) or 4-tert-butylcatechol (BuCA) and tin(II)-2-ethylhexanoate (SnOct2) as catalysts and a variation of the Lac/Cat ratio. Weight average molar masses (Mw) up to 170,000 g mol−1 were obtained with CA and up to 120,000 g mol−1 with BuCA. The cyclic structure of the resulting poly(l-lactide)s was proven by MALDI-TOF mass spectrometry and by comparison of their hydrodynamic volumes with those of commercial linear poly(l-lactide)s. The predominance of even-numbered cycles increased with lower temperatures and shorter polymerization times. This fnding indicates that the cyclic architecture is the results of a ring-expansion polymerization mechanism. Addition of silylated BuCA as co-catalyst was less favorable than addition of free BuCA.
L-Lactide was polymerized in bulk with tin(II)2-ethylhexanoate SnOct2) as catalyst and salicylic acid as cocatalyst. The Lac/Cat ratio, Cocat/Cat ratio, temperature and time were varied. Increasing Cocat/Cat ratios reduced both,polymerization rate and molecular weight. However,under optimized conditions high molar mass (Mw up to 178,000), colorless, cyclic polylactides were formed in a short time. A few polymerizations performed at 160 and 180°C with the combination of SnOct2 and silylated salicylic acid gave similar results. Neat tin II) salicylate was prepared from SnOct2 and used for REPs of L-lactide in bulk, but the results were not better than those obtained from combinations of SnOct2 and salicylic acid. Furthermore, dibutyltin salicylate was synthesized and used as catalyst for polymerizations of L-lactide in bulk at temperatures varying from 102 to 160°C. Cyclic polylactides with Mw’s up to 40,000 were the main reaction products. At 100–102°C a predominance of odd-numbered cycles was found proving a REP mechanism.
Matrix‐assisted ionization (MAI) mass spectrometry does not require voltages, a laser beam, or added heat to initiate ionization, but it is strongly dependent on the choice of matrix and the vacuum conditions. High charge state distributions of nonvolatile analyte ions produced by MAI suggest that the ionization mechanism may be similar to that of electrospray ionization (ESI), but different from matrix‐assisted laser desorption/ionization (MALDI). While significant information is available for MAI using mass spectrometers operating at atmospheric and intermediate pressure, little is known about the mechanism at high vacuum.
Eleven MAI matrices were studied on a high‐vacuum time‐of‐flight (TOF) mass spectrometer using a 266 nm pulsed laser beam under otherwise typical MALDI conditions. Detailed comparisons with the commonly used MALDI matrices and theoretical prediction were made for 3‐nitrobenzonitrile (3‐NBN), which is the only MAI matrix that works well in high vacuum when irradiated with a laser.
Screening of MAI matrices with good absorption at 266 nm but with various degrees of volatility and laser energies suggests that volatility and absorption at the laser wavelength may be necessary, but not sufficient, criteria to explain the formation of multiply charged analyte ions. 3‐NBN produces intact, highly charged ions of nonvolatile analytes in high‐vacuum TOF with the use of a laser, demonstrating that ESI‐like ions can be produced in high vacuum. Theoretical calculations and mass spectra suggest that thermally induced proton transfer, which is the major ionization mechanism in MALDI, is not important with the 3‐NBN matrix at 266 nm laser wavelength. 3‐NBN:analyte crystal morphology is, however, important in ion generation in high vacuum.
The 3‐NBN MAI matrix produces intact, highly charged ions of nonvolatile compounds in high‐vacuum TOF mass spectrometers with the aid of ablation and/or heating by laser irradiation, and shows a different ionization mechanism from that of typical MALDI matrices.
A series of phenolic-acid-based 2-oxazoline monomers with methoxysubstituted phenyl and cinnamyl side chains is synthesized and polymerized in a microwave reactor at 140 °C using methyl tosylate as the initiator. The obtained poly(2-oxazoline)s are characterized by NMR spectroscopy, MALDITOF mass spectrometry, and size-exclusion chromatography (SEC). Kinetic studies reveal that the microwave-assisted polymerization is fast and completed within less than ≈10 min for low monomer-to-initiator ratios of ≤25.
Polymers with number-average molar masses of up to 6500 g mol−1 and low dispersity (1.2–1.3) are produced. The aryl methyl ethers are successfully cleaved with aluminum triiodide/N,N′ diisopropylcarbodiimide to give a poly(2-oxazoline) with pendent catechol groups.
Mechanochemically synthesized metal–organic Framework material HKUST-1 in combination with acrylonitrile butadiene styrene polymer was used to form a polymer metal–organic framework composite material by a simple extruder.
This composite filament was used for 3D printing. Xray diffraction measurements were used to prove the homogeneous distribution of the metal–organic framework in the polymer on a centimeter scale, whereas X-ray Absorption Edge Tomography using a synchrotron radiation source was able to evaluate the 3D distribution of the metal–organic framework material both in the filament and the resultant printed sample with a resolution of a few lm. Our very first data indicate that, apart from a few clusters having significantly higher Cu concentration, HKUST-1 is distributed homogeneously down to the 100 lm length scale in both polymer bulk materials in the form of clusters with a size of a few lm. Absorption Edge Tomography in combination with data fusion also allows for the calculation of the metal–organic framework amount located on the external polymer surface.
The chemical and morphological stabilities of polymer segments in the near-surface layer were investigated by spectroscopic methods such as X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy. Model studies were undertaken with LangmuirBlodgett films, self-assembled monolayers and oligomer films. For thin polymer layers (30 to 500 nm), the changes in molecular-weight distributions of some polymers were investigated systematically by size exclusion chromatography, matrix-assisted laser desorption/ionizationtime-of-flight mass spectrometry and thermal-field flow fractionation for oxygen- and helium-plasma exposures. The polymer surfaces were found to be relatively stable at exposure to an oxygen low-pressure plasma up to ca. 2 s. This is important information to get maximum adhesion to metals in composites. In correlation to their redox potentials, potassium, aluminium and chromium react with oxygen functional groups at the polymer/metal interface. In a dedicated study, chromium was found to attack aromatic rings and form different reaction products.
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).
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.