A5085611781- Electrostatics and Colloid Interactions
- Material Dynamics and Properties
- Dielectric materials and actuators
- Advanced Sensor and Energy Harvesting Materials
- Fuel Cells and Related Materials
- Ferroelectric and Piezoelectric Materials
- Spectroscopy and Quantum Chemical Studies
- Nanopore and Nanochannel Transport Studies
- Pickering emulsions and particle stabilization
- Microfluidic and Bio-sensing Technologies
- Analytical Chemistry and Sensors
- Advanced Battery Technologies Research
- High voltage insulation and dielectric phenomena
- Phase Equilibria and Thermodynamics
- Surfactants and Colloidal Systems
- Advanced Theoretical and Applied Studies in Material Sciences and Geometry
- Conducting polymers and applications
- Membrane-based Ion Separation Techniques
- Microfluidic and Capillary Electrophoresis Applications
- Advanced Mathematical Modeling in Engineering
- Polymer Nanocomposites and Properties
- DNA and Nucleic Acid Chemistry
- Adsorption, diffusion, and thermodynamic properties of materials
- Chemical Thermodynamics and Molecular Structure
- Theoretical and Computational Physics
Joint Institute for High Temperatures
2014-2024
Heinrich Heine University Düsseldorf
2012-2024
Case Western Reserve University
2014-2024
University of Duisburg-Essen
2018-2020
Baku State University
2015
Russian Academy of Sciences
1996-2011
Joint Institute for Nuclear Research
2011
Forschungszentrum Jülich
2002-2005
Azerbaijan Technical University
1996
Eindhoven University of Technology
1995
In contrast to the comprehensive understanding of novel ferroelectric [i.e., relaxor (RFE) and antiferroelectric] behavior in ceramics, RFE double-hysteresis-loop (DHL) crystalline polymers have only been studied past fifteen years. A number applications such as electrostriction, electric energy storage, electrocaloric cooling realized by utilizing these properties. Nonetheless, fundamental behind behaviors is still missing for polymers. this feature article, we intend unravel basic physics...
Polymer/inorganic particle nanocomposites (or nanodielectrics) have attracted pronounced attention for electric energy storage applications, based on a hypothesis that polymer nanodielectrics could combine the high permittivity of nanoparticles and electrical breakdown strength matrix enhanced dielectric performance. Although higher discharged densities been reported numerous nanodielectrics, loss mechanisms, which are extremely important ultimate rarely discussed. In this work, we intend to...
With the modern development of power electrification, polymer nanocomposite dielectrics (or nanodielectrics) have attracted significant research attention. The idea is to combine high dielectric constant inorganic nanofillers and breakdown strength/low loss a matrix for higher energy density film capacitors. Although impressively has been achieved at laboratory scale, there still large gap from eventual goal nanodielectric In this review, we focus on essential material issues two types...
Abstract Piezoelectric polymers hold great potential for various electromechanical applications, but only show low performance, with | d 33 < 30 pC/N. We prepare a highly piezoelectric polymer ( = −62 pC/N) based on biaxially oriented poly(vinylidene fluoride) (BOPVDF, crystallinity 0.52). After unidirectional poling, macroscopically aligned samples pure β crystals are achieved, which high spontaneous polarization P s ) of 140 mC/m 2 . Given the theoretical limit s,β 188 neat crystal,...
A novel mechanism for counterion-mediated attraction between like-charged spherical macroions is proposed, which originates from a depletion zone of counterions nearly touching that induced by Coulomb interactions. Using computer simulations the primitive model, we show this effect dominates over electrostatic contribution in case strong coupling when all form quasi-two-dimensional layer on macroionic surface. Its range given typical spacing macroion
Poly(vinylidene fluoride) (PVDF)-based homopolymers and copolymers are attractive for a broad range of electroactive applications because their high dielectric constants. Especially, biaxially oriented PVDF (BOPVDF) films exhibit DC breakdown strength as that polypropylene films. In this work, we revealed the molecular origin constant via study commercial BOPVDF film. By determination amorphous phase in BOPVDF, value ca. 21-22 at 25 °C was obtained, three-phase (i.e., lamellar...
Abstract Despite extensive research on piezoelectric polymers since the discovery of poly(vinylidene fluoride) (PVDF) in 1969, fundamental physics polymer piezoelectricity has remained elusive. Based classic principle piezoelectricity, should originate from polar crystalline phase. Surprisingly, crystal contribution to strain coefficient d 31 is determined be less than 10%, primarily owing difficulty changing molecular bond lengths and angles. Instead, >85% Poisson's ratio, which closely...
Computer simulations and theory are used to systematically investigate how the effective force between two big colloidal spheres in a sea of small depends on basic (big-small small-small) interactions. The latter modeled as hardcore pair potentials with Yukawa tail which can be either repulsive or attractive. For small-small interaction, follows trends predicted by mapping onto an nonadditive mixture: both depletion attraction accumulation repulsion caused adsorbing ones obtained depending...
A recently developed mesoscopic solvent model with multiparticle-collision dynamics is applied to three-dimensional flows in a channel and without spherical obstacle. The advantage of gravitationally driven flow the over induced by pressure gradient calculation viscosity demonstrated. Three different algorithms for stochastic collision steps are investigated compared. In particular, we have examined an alternative algorithm relative velocities drawn from Maxwell-Boltzmann distribution at...
Crystallization represents the prime example of a disorder order transition. In realistic situations, however, container walls and impurities are frequently present hence crystallization is heterogeneously seeded. Rarely seeds perfectly compatible with thermodynamically favoured crystal structure thus induce elastic distortions, which impede further growth. Here we use colloidal model system, not only allows us to quantitatively control induced distortions but also visualize follow...
Recently, double hysteresis loop (DHL) behavior, which is advantageous for the high energy density and low loss dielectric application, was achieved in a poly(vinylidene fluoride-co-trifluoroethylene-co-chlorotrifluoroethylene)-graft-polystyrene [P(VDF-TrFE-CTFE)-g-PS(14%)] graft copolymer due to nanoconfinement effect. In this work, we continued investigate crystal orientation temperature effects on DHL behavior of copolymer. Based electric displacement–electric field (D–E) study, had...
We investigate the most basic situation of heterogeneous crystallization: crystallization hard-sphere colloids in presence a flat hard wall. Using combination confocal microscopy and nonequilibrium Brownian dynamics simulations, microscopic time-resolved information is obtained on an individual-particle level. Initially, particles near wall rearrange before extended regime crystal growth found. During growth, we can directly observe depletion zone fluid next to progressing crystal–fluid...
The effective force between two parallel DNA molecules is calculated as a function of their mutual separation for different valencies counterion and salt ions concentrations. Computer simulations the primitive model are used shape accurately modeled using geometrical shapes. We find that multivalent induce significant attraction whose strength can be tuned by averaged valency ions. physical origin traced back either to electrostatics or entropic contributions. For counterions monovalent...
We have used coarse-grained simulation methods to investigate the effect of stretching-induced structure orientation on proton conductivity Nafion-like polymer electrolyte membranes. Our simulations show that uniaxial stretching causes hydrophilic regions become elongated in direction. This change has a strong conductivity, which is enhanced along direction, while perpendicular stretched backbone reduced. In humidified membrane, also perfluorinated side chains tend orient axis. turn affects...
Mixing dielectric polymers with high permittivity (high-<italic>k</italic>) inclusions can boost their actuation and energy storage properties.
Abstract Relaxor ferroelectric polymers exhibiting a giant electrocaloric effect (ECE) can potentially be used to create next‐generation solid‐state coolers. Under an electric field, poly(vinylidene fluoride‐trifluoroethylene‐chlorofluoroethylene) terpolymer goes through large dipolar entropy change producing high adiabatic temperature (Δ T ECE ). This work resolves the molecular origins of behind field‐induced dipole switching. A Fourier transform infrared spectroscopy equipped with voltage...
Although high piezoelectric coefficients have recently been observed in poly(vinylidene fluoride-co-trifluoroethylene) [P(VDF-TrFE)] random copolymers, they low Curie temperatures, which makes their piezoelectricity thermally unstable. It has challenging to achieve performance from the more stable PVDF homopolymer. In this report, we describe how high-power ultrasonic processing was used induce a hard-to-soft transition and improve coefficient d31 neat PVDF. After ultrasonication for 20 min,...
The distance-resolved effective forces between two spherical, highly charged colloidal macroions are calculated by computer simulation within the primitive model of strongly asymmetric electrolytes. In particular we consider case macroions, i.e., particles with different charges and radii, as well added salt ions. Different parameter sets corresponding to typical experimental samples investigated. results compared predictions traditional linear screening theory Derjaguin Landau [Acta...
Controlled actuation of electroactive polymers with embedded high dielectric nanoparticles is theoretically analyzed.