Ulrich Scheler

Ulrich Scheler
Leibniz Institute of Polymer Research Dresden | ipfdd · Department of Polyelectrolytes and Dispersions

Dr.

About

147
Publications
14,239
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2,521
Citations
Citations since 2016
38 Research Items
1121 Citations
2016201720182019202020212022050100150200
2016201720182019202020212022050100150200
2016201720182019202020212022050100150200
2016201720182019202020212022050100150200
Additional affiliations
January 2008 - present
Tokyo University of Agriculture and Technology
January 2005 - present
March 1996 - present
Independent Researcher
Independent Researcher

Publications

Publications (147)
Article
Epoxidized natural rubber (ENR) was grafted with imidazolium ions, giving the materials self-healing and re-processing properties. These imidazolium ions in the form of neutral ionic repeating units transformed the polyisoprene-based polymer chains into ionomers. Fourier-transform infrared spectroscopy (FTIR) and solid-state nuclear magnetic resona...
Article
Full-text available
Anode‐free battery concept was proposed to pursue the aspiration of energy‐dense, rechargeable metal batteries, but this has not been achieved with dual‐ion batteries. Herein, we demonstrate the first anode‐free Zn‐graphite battery enabled by efficient Zn plating‐stripping onto silver‐coated Cu substrate. The silver coating guides uniform Zn deposi...
Article
Flow patterns including counter-flow and flow reversal effects have been studied by a combination of nuclear magnetic resonance flow imaging and numerical modeling using the finite volume method in the open-source computational fluid mechanics package OpenFOAM. Two cylindrical geometries have been used: In a concentric double-cylinder system the fl...
Article
Full-text available
Rechargeable aluminium (Al) batteries (RABs) have long been pursued due to the high sustainability and three-electron-transfer properties of Al metal. However, limited redox-chemistry is available for rechargeable Al batteries, which restricts the exploration of cathode materials. Herein, we demonstrate an efficient Al-amine battery based on a quat...
Article
Full-text available
Rechargeable aluminium (Al) batteries (RABs) have long been pursued due to the high sustainability and three-electron-transfer properties of Al metal. However, limited redox-chemistry is available for rechargeable Al batteries, which restricts the exploration of cathode materials. Herein, we demonstrate an efficient Al-amine battery based on a quat...
Article
Despite the vast array of solution- and solid-state bio-analytical, bioelectronic and optoelectronic applications for cationic polythiophenes (CPTs), the number of studies focused on the role hydrogen bonding (H-bonding) between these...
Article
The strong polycation poly(diallyldimethylammonium chloride) (PDADMAC) and the weak polyanion poly(ethylene-alt-maleic acid) (P(E-alt-MA)) were used to build polyelectrolyte multilayers (PEMs) up to 31 layers. A spin-label (SL) was covalently attached to the polyanion for studying the rotational dynamics of the polyacid backbone in a swollen state...
Article
Full-text available
The rotational dynamics of the spin‐labeled polyacid poly(ethylene‐alt‐maleic acid) (P(E‐alt‐MA)) in polyelectrolyte complexes (PECs) formed with the polycations poly(allylamine hydrochloride) (PAH) and poly(diallyldimethylammonium chloride) (PDADMAC) are studied by electron paramagnetic resonance (EPR) spectroscopy as a function of the mixing rati...
Article
In recent years, chitosan has attracted considerable interest in many fields due to its sufficient charge density under biological, non-hazardous conditions. Since chitosan originates from natural resources and has two different monomer units, its characterization must be carried out in a goal-oriented and precise manner. This work focuses on the c...
Article
The study confirms the interaction of sulfate ions (SO4²⁻) into the polymer chains of chitosan under acidic conditions. As a result the crystallinity of chitosan decreases with (1) increasing protonation of the amino groups and (2) increasing SO4²⁻ concentration. The adsorption of iron ions (Fe2+/3+) resulting from (FeSO4)aq onto the chitosan surfa...
Article
Full-text available
The intrinsic advantages of metallic Zn, like high theoretical capacity (820 mAh g−1), high abundance, low toxicity, and high safety have driven the recent booming development of rechargeable Zn batteries. However, the lack of high‐voltage electrolyte and cathode materials restricts the cell voltage mostly to below 2 V. Moreover, dendrite formation...
Article
A new method for the study of the substitution of polyelectrolytes in polyelectrolyte complexes is demonstrated. A spin-labeled weak polyanion poly(ethylene-alt-maleic acid) (P(E-alt-MA)) has been used to study the substitution of this polyanion in the polyelectrolyte complex with the strong polycation poly(diallyldimethylammonium chloride) (PDADMA...
Article
In living cells, biomacromolecules are exposed to a highly crowded environment. The cytoplasm, the nucleus, and other organelles are highly viscous fluids that differ from dilute in vitro conditions. Viscosity, a measure of fluid internal friction, directly affects the forces that act on immersed macromolecules. Although active motion of this visco...
Article
A nitroxide spin label has been covalently attached to the weak polyelectrolyte poly(ethylene-alt-maleic acid) (P(E-alt-MA)) to study the rotational dynamics of the polyacid backbone in swollen polyelectrolyte multilayers (PEMs) formed by P(E-alt-MA) and the oppositely charged weak polycation poly(allylamine hydrochloide) (PAH) by continuous wave e...
Article
Full-text available
The local dynamics in polymer melts and the impact of external shear in a Couette geometry have been investigated using rheological nuclear magnetic resonance (NMR). The spin-spin relaxation time, T2, which is sensitive to chain-segment motion, has been measured as a function of shear rate for two samples of poly(dimethylsiloxane). For the low-mole...
Article
Full-text available
Rubber composites were prepared by mixing bromobutyl rubber (BIIR) with silica particles in the presence of 1-butylimidazole. In addition to pristine (precipitated) silica, silanized particles with aliphatic or imidazolium functional groups, respectively, were used as filler. The silanization was carried out either separately or in situ during comp...
Article
A sol-gel transformation of liquid silica precursor to solid silica particles was carried out in a one pot synthesis way where a solution of styrene butadiene elastomer (S-SBR) was present. The composites, thus produced, offered remarkable improvements of mechanical and dynamic mechanical performances as compared with precipitated silica. The morph...
Article
Full-text available
In this work, we show that it is possible to overcome the limitations of solid-state MRI for rigid tissues due to large line broadening and short dephasing times by combining Magic Angle Spinning (MAS) with rotating pulsed field gradients. This allows recording ex vivo³¹P 3D and 2D slice-selected images of rigid tissues and related biomaterials at...
Article
Full-text available
Solid-state nuclear magnetic resonance (NMR) spectroscopy allows for the identification of inorganic species during the biomineral formation, when crystallite particles visible in direct imaging techniques have not yet been formed. The bone blocks surrounding dental implants in minipigs were dissected after the healing periods of two, four, and eig...
Article
A spin label has been covalently attached to the weak polyanion poly(ethylene-alt-maleic acid) (P(E-alt-MA)) to study the segmental dynamics of the polyanion backbone in polyelectrolyte complex coacervate phases formed with oppositely charged polycations such as poly(diallyldimethylammonium chloride) (PDADMAC), linear poly(ethylenimine) (l-PEI) and...
Article
Full-text available
Free-standing polyelectrolyte multilayer membranes have been formed by the layer-by-layer technique using a dip-coating apparatus. The polymer-chain mobility has been studied by 1H relaxation in the rotating frame T1rho NMR with 13C chemical shift resolution. For each of the individual polymers a single relaxation component has been observed for al...
Article
Shear stress can induce structural deformation of proteins, which might result in aggregate formation. Rheo-NMR spectroscopy has the potential to monitor structural changes in proteins under shear stress at the atomic level; however, existing Rheo-NMR methodologies have insufficient sensitivity to probe protein structure and dynamics. Here we prese...
Article
Full-text available
One consequence of demographic change is the increasing demand for biocompatible materials for use in implants and prostheses. This is accompanied by a growing number of experimental animals because the interactions between new biomaterials and its host tissue have to be investigated. To evaluate novel materials and engineered tissues the use of no...
Data
Clinical results—Additional MRI and histological findings. (PDF)
Data
Bland-Altman analysis and plot. (PDF)
Data
Repeated measurements—Influence of the slice position. (PDF)
Article
The dynamics of spin-labeled poly(acrylic acid) (PAA) in polyelectrolyte complexes (PECs) has been studied by EPR. It has been found that the segmental mobility of the PAA in the PECs is nearly constant in the pH range 10 to 5 but decreases dramatically for pH < 5. Recently, we have studied the dynamics of spin-labeled poly(ethylene-alt-maleic acid...
Article
Full-text available
Hexagonal Aluminium nitride (h-AlN) is an important wide-bandgap semiconductor material which is conventionally fabricated by high temperature carbothermal reduction of alumina under toxic ammonia atmosphere. Here we report a simple, low cost and potentially scalable mechanochemical procedure for the green synthesis of nanostructured h-AlN from a p...
Article
Three rectorite samples from the Beatrix Gold Mine, South Africa were characterized. Scanning electron microscopy revealed a layered morphology. High resolution transmission microscopy showed well distinguished light and dark layers of about 2.20 nm consistent with the 1:1 interstratified mica-smectite nature. X-ray diffraction measurements confirm...
Article
Full-text available
Read the article online: http://atlasofscience.org/strong-magnets-to-investigate-novel-dental-implants/#more-11696
Conference Paper
Full-text available
Nuclear Magnetic Resonance(NMR) is applied for the investigation of polymernanocomposites.Solid-stateNMR is applied to study the modification steps to compatibilize layered double hydroxides with non-polar polymers.¹H relaxationNMR gives insight on the polymer dynamics over a wide range of correlation times. For the polymer chain dynamics the trans...
Article
Full-text available
The mesocrystal system fluoroapatite - gelatine grown by double-diffusion is characterized by hierarchical composite structure on a mesoscale. In the present work we apply solid state NMR to characterize its structure on the molecular level and provide a link between the structural organisation on the mesoscale and atomistic computer simulations. T...
Article
A nitroxide spin label has been covalently linked to the weak polyacid poly(ethylene-alt-maleic acid) (P(E-alt-MA)) to study the rotational mobility of the polyacid backbone in polyelectrolyte complexes (PEC) formed with the oppositely charged strong polycation poly(diallyldimethylammonium chloride) (PDADMAC) in dependence on the pH of the dispersi...
Article
The influence of maltose-modified poly(propylene imine) (PPI) dendrimers on dimyristoylphosphatidylcholine (DMPC) or dimyristoylphosphatidylcholine/dimyristoylphosphatidylglycerol (DMPC/DMPG) (3%) liposomes was studied. Fourth generation (G4) PPI dendrimers with primary amino surface groups were partially (open shell glycodendrimers - OS) or comple...
Article
Medical imaging is an important tool for the post-operative checkup of an accurate position of an implant as well as for monitoring the integration in the adjacent tissue that may influence the success of a medical device. Unfortunately, the possibility to use imaging methods is associated with the implant material and all the established metallic...
Conference Paper
Full-text available
Polyetheretherketone (PEEK) was commercialized for applications in the automotive, aviation and electrical industry since the 1980s. The outstanding chemical resistance, stability against high energy radiation, suitable mechanical properties and its biocompatibility makes the polymer attractive for application as biomaterial 1. Compared to classica...
Article
Spin-labeled poly(ethylene-alt-maleic acid) (SL-P(E-alt-MA)) with 2.5 mol% spin-labeled repeat units is prepared to study the interaction of this polyanion with an oppositely charged polyelectrolyte by electron paramagnetic resonance (EPR) spectroscopy. The internal rotation of the spin label and the segmental rotational mobility of the polyanion i...
Article
The model system fluorapatite-gelatine allows to mimic formation conditions on a lower level of complexity compared to the formation conditions of natural dental and bone tissues. Here, we report on solid-state NMR investigations to examine the structure of fluorapatite-gelatine nanocomposites on a molecular level with particular focus on organic-i...
Article
High-resolution solid-state NMR based on combined rotation and multipulse spectroscopy (CRAMPS) has been applied to study chemical structures of dental tissues. The samples of human enamel, crown dentine and root dentin studied in this work were used without chemical pre-treatment. The quantitative 1H NMR spectra permit an assignment to different s...
Article
Abstract Poly(methyl methacrylate)/silica (PMMA/SiO x) nanocomposites were synthesized via sol–gel method and studied by various techniques. The dispersion of the silica particles (10–100 nm) in the matrix was probed by transmission electron microscopy (TEM), while solid‐state NMR and Raman spectroscopy detected the formation of an inorganic networ...
Article
Fluorination of graphite at room temperature allows producing graphite fluoride compounds with a controlled content of fluorine. Here we combine solid-state NMR spectroscopy and DFT calculations to study the structure and reveal the fluorine patterning in graphite fluorides C2Fx intercalated with acetonitrile. Two major chemical states of carbon, n...
Article
Full-text available
The initial stage of the NMR H-1 T-1 relaxation of well-defined polypropylene-montmorillonite nanocomposites was investigated at two different magnetic fields of 0.54 and 7.05 T. At 0.54 T, two periods can be distinguished during the first 30 ms after a saturation pulse train. Both periods scale linearly with the square root of the recovery time. T...
Article
Full-text available
NMR pulse gradient spin echo is the most efficient method for non-invasive elucidation of molecular transport in heterogeneous media. With a proper interpretation of experimental data, the method can also be applied to investigate molecular self-diffusion in pores small enough that the characteristic diffusion times are much shorter than time, need...
Article
The condensation of counterions is an important aspect of charged macromolecules. Therefore an experimental characterization of the condensation of counterions is desirable. In this contribution two experimental techniques for the characterization of counterion condensation are introduced and compared: Anomalous Small Angle X-Ray Scattering (ASAXS)...
Chapter
Electrophoresis NMR or electrophoretic NMR is the application of pulsed field gradient NMR to the investigation of electrophoretic motion of charged moieties in solution, including ions, molecules, vesicles, and complexes. The application of a strong electric field requires a dedicated NMR probehead. Designs of increasing complexity are discussed,...
Article
A nitroxide spin label has been covalently attached to the polyelectrolyte poly(ethylene-alt-maleic acid) (P(E-alt-MA)) to study the interaction between this weak polyanion, the oppositely charged strong polycation poly(diallyldimethylammonium chloride) (PDADMAC) and water in swollen polyelectrolyte multilayers (PEM) by electron paramagnetic resona...
Article
Full-text available
PAMAM dendrimers are used as a model system to investigate the effects of counterion condensation and the effective charge for spherical polyelectrolytes. Because of their amino groups, PAMAM dendrimers are weak polyelectrolytes. Lowering the pH results in an increasing protonation of the amino groups which is monitored via the proton chemical shif...
Article
Proton dynamics in pristine and organically-modified layered double hydroxide has been studied by 1H T1ρ. Inverse Laplace transform with spectral resolution results in a correlation of T1ρ and chemical shift.In LDH two contributions are resolved. They are assigned to the metal hydroxides, forming the LDH sheets (4–8 ms), and mobile interlayer water...
Article
Low-field NMR in a Halbach magnet has been used for the in-situ investigation of polymers under mechanical stress. Low-field NMR at a Larmor frequency of 32 MHz is particularly suited for the investigation of magnetic resonance relaxation and residual dipolar couplings. The method has been demonstrated on an elastomer and has subsequently been appl...
Article
We report the identification and elucidation of the mechanistic role of molecular precursors and nanoscale (1-3 nm) intermediates with intrinsic curvature in the formation of single-walled aluminosilicate nanotubes. We characterize the structural and compositional evolution of molecular and nanoscale species over a length scale of 0.1-100 nm by ele...
Article
The local environment in biomimetic hydroxy-apatite (HAp) nanocomposites containing 0 and 33 wt % gelatin was characterized by 31P solid-state NMR spectroscopy. The presence of crystalline HAp and amorphous calcium phosphate phases was found in both materials. The latter can appear at the grain surfaces or at the boundaries of the crystalline phase...
Article
The influence of the counterions on the hydrodynamic size and the effective charge of poly(styrene sulfonate) has been investigated applying a combination of pulsed-field gradient (PFG) NMR and electrophoresis NMR. From the diffusion coefficient, determined by PFG NMR the hydrodynamic radius as a measure of the size is inferred. Electrophresis NMR...
Chapter
Full-text available
Mechanical shear is part of processing steps of polymers in the melt. Shear influences polymer dynamics and chain order in the melt. The effect of mechanical shear on the NMR relaxation behaviour of polymer melts has been studied. A dedicated probehead capable for high-temperature rheo NMR has been developed and applied. Both the transverse and the...
Article
First-principles quantum mechanical calculations of NMR chemical shifts and quadrupolar parameters have been carried out to assign the (27)Al MAS NMR resonances in gibbsite. The (27)Al NMR spectrum shows two signals for octahedral aluminum revealing two aluminum sites coordinated by six hydroxyl groups each, although the crystallographic positions...
Article
The effective charge of poly(styrenesulfonate) has been investigated by diffusion and electrophoresis nuclear magnetic resonance (NMR). While the electrophoretic mobility is determined in the electrophoresis NMR experiment, the hydrodynamic friction is determined from diffusion NMR using Einstein's formula. On the timescale of the NMR experiment a...
Article
The local structure of pristine and surfactant-modified aluminum layered double hydroxides (LDH) has been characterized by (27)Al and (1)H solid-state NMR. Values for the (27)Al quadrupole Coupling constants and the isotropic chemical shifts obtained from (27)Al triple-quantum (3Q)MAS NMR have been applied to fit the one-dimensional (27)Al MAS spec...
Article
A novel one-step method has been developed to synthesize organically modified layered double hydroxide under ambient condition and without requirement of carbonate-free condition. This method has been found to be effective in the presence of several competitive anions and provides modified products with improved homogeneity, crystallinity, etc., as...