A5059929481- Material Dynamics and Properties
- Thermodynamic properties of mixtures
- Ionic liquids properties and applications
- Glass properties and applications
- Advanced Battery Materials and Technologies
- Spectroscopy and Quantum Chemical Studies
- Liquid Crystal Research Advancements
- Surfactants and Colloidal Systems
- Rheology and Fluid Dynamics Studies
- Solid-state spectroscopy and crystallography
- Conducting polymers and applications
- NMR spectroscopy and applications
- Polymer Nanocomposites and Properties
- Phase Equilibria and Thermodynamics
- Electrochemical Analysis and Applications
- Methane Hydrates and Related Phenomena
- Photochemistry and Electron Transfer Studies
- Fuel Cells and Related Materials
- Polymer composites and self-healing
- Polymer crystallization and properties
- Advancements in Battery Materials
- Theoretical and Computational Physics
- Crystallography and molecular interactions
- Advanced Battery Technologies Research
- Analytical Chemistry and Sensors
Oak Ridge National Laboratory
2021-2024
TU Dortmund University
2014-2024
Universität Innsbruck
2019
University of Tennessee at Knoxville
2016-2017
University of Bayreuth
2003-2012
Arizona State University
2012
Roskilde University
2012
Russian Academy of Sciences
2008
Significance Water is not only the most important liquid for life on Earth, but also one of anomalous liquids. These anomalies become evident in supercooled state at subzero temperatures. We show from dielectric and calorimetric studies that water deeply regime, below –120 °C, can even exist as two distinct, ultraviscous liquids ambient pressure, a low- (LDL, 0.92 g/cm 3 ) high-density (HDL, 1.15 ), which both remain metastable, equilibrium many hours above their glass transition...
Besides being fundamental for life on Earth, water is one of the complex materials in nature. Due to unusual properties hydrogen bonds has a large number phases as function temperature and pressure. Furthermore, phase transitions between these different are still object much discussion. In this Colloquium nature amazing reviewed.
The transport of protons is critical in a variety bio- and electro-chemical processes technologies. Grotthuss mechanism considered to be the most efficient proton mechanism, generally implying transfer between 'chains' host molecules via elementary reactions within hydrogen bonds. Although proposed this concept more than 200 years ago, only indirect experimental evidence has been observed. Here we report first observation pure 85% aqueous phosphoric acid. Employing dielectric spectroscopy,...
Monohydroxy alcohols show a structural relaxation and at longer time scales Debye-type dielectric peak. From spin-lattice experiments using different nuclear probes, an intermediate, slower-than-structural dynamics is identified for n-butanol. Based on these findings translational diffusion measurements, model of self-restructuring, transient chains proposed. The demonstrated to explain consistently the so-far puzzling observations made this class hydrogen-bonded glass forming liquids.
We present detailed studies of ionic conductivity in several polymerized liquids (PolyILs) with different size mobile ions. Presented analysis revealed that charge diffusion PolyILs is about 10 times slower than ion diffusion, suggesting strong ion–ion correlations reduce conductivity. The activation energy for the shows a nonmonotonous dependence on size, indicating competition between Coulombic and elastic forces controlling transport PolyILs. former dominates mobility small ions (e.g.,...
Combining broadband impedance spectroscopy, differential scanning calorimetry, and nuclear magnetic resonance we analyzed charge mass transport in two polymerized ionic liquids one of their monomeric precursors. In order to establish a general procedure for extracting single-particle diffusivity from conductivity spectra, critically assessed several approaches previously employed describe the onset diffusive dynamics electrode polarization ion conducting materials. Based on analysis...
Liquids composed of small-molecule monohydroxy alcohols are demonstrated to display rheological behavior typical for oligomeric chains. This observation was made possible by experiments in which more than seven decades frequency and five on the mechanical modulus scale covered. The singly hydrogen-bonded were chosen because they significant, but surprisingly poorly understood effects intermolecular association. Based present shear study, one can apply theoretical concepts polymer science...
Dielectric loss spectra covering 13 decades in frequency were collected for 2-ethyl-1-hexanol, a monohydroxy alcohol that exhibits prominent Debye-like relaxation, typical several classes of hydrogen-bonded liquids. The thermal variation the dielectric absorption amplitude agrees well with hydrogen-bond equilibrium population, experimentally mapped out using near infrared (NIR) and nuclear magnetic resonance (NMR) measurements. Despite this agreement, temperature-jump NIR spectroscopy...
Liquid monohydroxy alcohols exhibit unusual dynamics related to their hydrogen bonding induced structures. The connection between structure and is studied for liquid 1-propanol using quasi-elastic neutron scattering, combining time-of-flight spin-echo techniques, with a focus on the at length scales corresponding main peak pre-peak of factor. At peak, structural relaxation times are probed. These correspond well mechanical calculated from literature data. pre-peak, H-bonded structures,...
Abstract Supramolecular adhesives are attracting considerable attentions owing to their dynamic and reversible bonding, while the complex curing conditions poor performance under extreme severely restrict applicability. Herein, a series of tetra‐crown ether‐terminated polyethylene glycol (TCE‐PEG) presented in which plenty supramolecular interactions, including Van der Waals, hydrogen π–π staking, metal coordination, electrostatic ones, provide strong adhesion on multiple types substrates....
Significance Water is by far the most important and intriguing liquid. Despite relative simplicity of its chemical structure there are many puzzling properties water that remain focus active discussions. Our studies revealed an unusually strong isotope effect extraordinarily slow temperature variation structural relaxation at low temperatures. We show anomalous behavior deeply supercooled affected quantum effects, usually considered negligible for glass transition. However, in they...
There has been a long controversy regarding the glass transition in low-density amorphous ice (LDA). The central question is whether or not it transforms to an ultraviscous liquid state above 136 K at ambient pressure prior crystallization. Currently, most widespread interpretation of experimental findings terms transformation superstrong K. In last decade some work also devoted study high-density (HDA) which focus present review. At HDA metastable against both I and LDA, whereas > 0.2 GPa...
Dielectric spectroscopy, rheology, and differential scanning calorimetry were employed to study the effect of chain-end hydrogen bonding on dynamics hydroxyl-terminated polydimethylsiloxane. We demonstrate that has a strong influence both segmental slower in systems with low molecular weights. In particular, decrease chain length leads an increase glass transition temperature, viscosity, fragility index, at variance usual behavior nonassociating polymers. The supramolecular association...
One century ago pioneering dielectric results obtained for water and n-alcohols triggered the advent of molecular rotation diffusion theory considered by Debye to describe primary absorption in these liquids. Comparing dielectric, viscoelastic, light scattering we unambiguously demonstrate that structural relaxation appears only as a high-frequency shoulder spectra water. In contrast, main peak is related supramolecular structure, analogous Debye-like observed mono-alcohols.
We performed rheological measurements of the typical deep eutectic solvents (DESs) glyceline, ethaline, and reline in a very broad temperature dynamic range, extending from low-viscosity to high-viscosity supercooled-liquid regime. find that mechanical compliance spectra can be well described by random free-energy barrier hopping model, while dielectric on same materials involve significant contributions arising reorientational dynamics. The temperature-dependent viscosity structural...
The present work studies the mechanisms controlling energy barrier for ion hopping in conducting polymers. Polymer electrolytes usually show Arrhenius-like temperature dependence of conductivity relaxation time (characteristic local rearrangements) at temperatures below their glass transition Tg. However, our analysis reveals that Arrhenius fit this regime leads to unphysically small prefactors, τ0 ≪ 10–13 s. Imposing a value s parameter renders fairly unexpected result charge transport...
This study investigates the impact of ceramic particle size on bulk and interfacial ion transport properties composite polymer electrolytes. The particles used for this are micrometer-sized commercial lithium lanthanum titanate (LLTO) powders LLTO nanorods (NR) prepared in laboratory. matrices vinylene carbonate (VEC) based single-ion-conducting (SIC) dual-ion-conducting (DIC) Our results reveal that addition NR improved transport, while is ineffective or even detrimental. We ascribe these...
The enzymatic hydrolysis of polyamides offers a promising approach to reduce the environmental impact chemical recycling by enabling lower reaction temperatures, eliminating toxic organic solvents, and enhancing product selectivity....
We utilize NMR field cycling relaxometry to study the crossover from glassy dynamics ($t\ensuremath{\gtrsim}{\ensuremath{\tau}}_{\ensuremath{\alpha}}$) through Rouse reptation behavior in a series of monodisperse polybutadienes with molecular weights $M=355$ $817\text{ }000\text{ }\text{ }\mathrm{g}/\mathrm{mol}$. separate characteristic polymer total spectrum dominated by dynamics. The show typical relaxation features that grow $M$ and saturate at high $M$. Comparing theory, we determine...
The susceptibility spectra of ten molecular glass formers are completely interpolated by an extension the generalized gamma distribution correlation times. data cover at least 15 decades in frequency and interpolation includes both alpha peak excess wing. It is shown that line shape parameters time constant relaxation related to each other. Master curves identified a scaling procedure involves only three parameters, namely, transition temperature T(g), fragility m, wing exponent T(g). This...