A5081267379- Ionic liquids properties and applications
- Material Dynamics and Properties
- Advanced Battery Materials and Technologies
- Phase Equilibria and Thermodynamics
- Polymer Nanocomposites and Properties
- Advanced Battery Technologies Research
- Advancements in Battery Materials
- Liquid Crystal Research Advancements
- Energetic Materials and Combustion
- Rheology and Fluid Dynamics Studies
- Nanotechnology research and applications
- Carbon Nanotubes in Composites
- Extraction and Separation Processes
- Spectroscopy and Quantum Chemical Studies
- Fuel Cells and Related Materials
- Fullerene Chemistry and Applications
- High-pressure geophysics and materials
- Advanced battery technologies research
- Molecular spectroscopy and chirality
- Fluid Dynamics Simulations and Interactions
- Thermodynamic properties of mixtures
- Polymer crystallization and properties
- Membrane-based Ion Separation Techniques
- Crystallization and Solubility Studies
- Machine Learning in Materials Science
University of Utah
2009-2024
University of Colorado Boulder
2013-2024
Salt Lake Regional Medical Center
2016-2021
Wasatch Molecular (United States)
2010-2019
University of Illinois Urbana-Champaign
2003-2007
New Mexico Institute of Mining and Technology
2000
Freeze Fracture Transmission Electron Microscopy (FFTEM) study of the nanoscale structure so-called "twist-bend" nematic (NX) phase cyanobiphenyl (CB) dimer molecule CB(CH2)7CB reveals a stripe texture fluid layers periodically arrayed with bulk spacing d ~ 8.3 nm. Fluidity and rigorously maintained produce long-range-ordered layered focal conic domains. Absence lamellar x-ray reflection at wavevector q 2{\pi}/8 nm-1 or its harmonics in synchrotron-based scattering experiments indicates that...
The microscopic polymer reference interaction site model theory of nanocomposites composed flexible chains and spherical nanoparticles has been employed to study second virial coefficients spinodal demixing over a wide range interfacial chemistry, chain length, particle size conditions. For hard fillers, two distinct phase separation behaviors, separated by miscibility window, are generically predicted. One curve occurs at relatively low monomer−particle attraction strength corresponds very...
A detailed computational study of the potential mean force between a pair spherical particles dissolved in homopolymer melt has been performed using microscopic liquid state theory. The role particle-to-monomer diameter ratio, degree polymerization, strength and spatial range monomer−particle attractions, direct interfiller attractions established. Beyond small particle regime, scales linearly with ratio. This simple scaling allows construction master curves quantification material specific...
The twist-bend nematic liquid crystal phase is a three-dimensional fluid in which achiral bent molecules spontaneously form an orientationally ordered, macroscopically chiral, heliconical winding of ten nanometer-scale pitch the absence positional ordering. Here, structure dimer CB7CB and its mixtures with 5CB characterized, revealing hidden invariance self-assembly CB7CB, such that over wide range concentrations temperatures, helix cone angle change as if ground state for TB inextensible...
The Polymer Reference Interaction Site Model (PRISM) theory is employed to investigate structure, effective forces, and thermodynamics in dense polymer-particle mixtures the one two particle limit. influence of size, degree polymerization, polymer reduced density established. In athermal limit, surface excess negative implying an entropic dewetting interface. induced depletion interactions are quantified via particle-particle pair correlation function potential mean force. A transition from...
Small angle neutron scattering studies on polystyrene loaded with spherical silica nanoparticles under contrast-matched conditions unequivocally show that chain conformations follow unperturbed Gaussian statistics independent of molecular weight and filler composition. Liquid state theory calculations are consistent this conclusion also predict filler-induced modification interchain polymer correlations which have a distinctive signature is in nearly quantitative agreement our observations.
A fundamental understanding of solid electrolyte interphase (SEI) properties is critical for enabling further improvement lithium batteries and stabilizing the anode–electrolyte interface. Mechanical transport two model SEI components were investigated using molecular dynamics (MD) simulations a hybrid MD-Monte Carlo (MC) scheme. many-body polarizable force field (APPLE&P) was employed in all simulations. Elastic moduli conductivity SEIs comprised dilithium ethylene dicarbonate (Li2EDC)...
Organic carbonate-based electrolytes blended with ionic liquids exhibit improved electrochemical properties, as demonstrated by experiments and MD simulations.
Surface active per- and polyfluoroalkyl substances (PFAS) show complex self-assembly behavior in aqueous environments.
Microscopic polymer liquid state theory is employed to study the real space pair correlation functions and collective scattering structure factors of melt nanocomposites composed hard spheres adsorbing homopolymers over length scales ranging from monomeric macroscopic. Increasing filler volume fraction has a profound effect on matrix, inducing oscillatory reorganization scale commensurate with nanoparticle diameter. The near contact interfacial monomer−filler correlations are suppressed by...
Previous applications of density functional (DF) theory required a single chain Monte Carlo simulation to be performed within self-consistent loop. In the current work, methodology is developed which permits taken out iterative Consequently, calculation self-consistent, medium-induced potential, or field, decoupled from simulation. This approach different densities, forms UM(r), and wall–polymer interactions investigated The increase in computational efficiency immense.
Molecular dynamics (MD) simulations of uniaxial shock compression along the [100] and [001] directions in α polymorph hexahydro-1,3,5-trinitro-1,3,5-triazine (α-RDX) have been conducted over a wide range pressures using constant stress Hugoniostat method [Ravelo et al., Phys. Rev. B 70, 014103 (2004)]. We demonstrate that is suitable for studying atomic-scale models energetic materials without necessity to consider extremely large simulation cells required an explicit wave simulation....
Extensive atomistic molecular dynamics (MD) simulations employing a polarizable force field have been conducted to study hydrated anion exchange membranes comprised of poly(p-phenylene oxide) (PPO) homopolymer functionalized with quaternary ammonium cationic side groups and hydroxide anions. Representative different structures investigated correlations between polymer architecture, morphology transport properties membranes. Specifically, polymers five (R1: -CH3, R2: -C2H5, R3: -C3H7, R4:...
Utilizing a first-principles-based coarse-grained implicit solvent model, we have investigated the self-association of C60 fullerenes that been symmetrically modified with six grafted poly(ethylene oxide) (PEO) chains in aqueous solution. Despite highly symmetric nature pair interactions between PEO-grafted fullerenes, their supramolecular assemblies are anisotropic and resemble linear clusters formed Stockmayer fluids. The dipole-like interaction these results from shielding by PEO,...
Isothermal compression of poly (dimethylsiloxane), 1,4-poly(butadiene), and a model Estane (in both pure form nitroplasticized composition similar to PBX-9501 binder) at pressures up 100 kbars has been studied using atomistic molecular dynamics (MD) simulations. Comparison predicted compression, bulk modulus, U(s)-u(p) behavior with experimental static dynamic data available in the literature reveals good agreement between experiment simulation, indicating that MD simulations utilizing...
Understanding the behavior of aqueous solutions containing tetraalkylammonium (TAA) cations is great significance in a number applications, including polymer membranes for fuel cells. In this work, polarizable force field has been used to perform atomistic molecular dynamics (MD) simulations tetramethylammonium (TMA) or tetrabutylammonium (TBA) and Br counterions. Extensive MD TMA-Br/water TBA-Br/water systems were conducted as function solution composition (ion pair:water molar ratios 1:10,...
Understanding the failure mechanisms of solid electrolyte interphases (SEI) is important for silicon electrodes because their volume expands substantially during lithiation. This work discusses material point method simulations SEI lithiation nanopillars. We demonstrate that considering films as brittle, elastic materials does not allow fracture would be consistent with experimental observations. However, constitutive models include plastic deformation and result in ductile are very good...
The unusually high heats of vaporization room-temperature ionic liquids (RTILs) complicate the utilization thermal evaporation to study liquid reactivity. Although effusion RTILs into a reaction flow-tube or mass spectrometer is possible, competition between and decomposition RTIL can greatly increase complexity observed products. In order investigate kinetics hypergolic RTIL, 1-butyl-3-methylimidazolium dicyanamide (BMIM+DCA-) was aerosolized reacted with gaseous nitric acid, products were...
Recently, new thermotropic ionic liquid crystals (LCs) with a hexyl-linked tris(imidazolium bromide) core and two terminal alkyl chains were synthesised characterised. To explore the effect of different counter-ions on LC behaviour this system, derivatives BF4− Tf2N− prepared analysed. Five found to exhibit behaviour. The 12-, 14- 16-carbon tail compounds form SmA phases. 18- 20-carbon homologues what appears be smectic phase but are weakly mesogenic harder characterise. Only exhibited...
The influence of water on the structure a prototype ionic liquid (IL) 1-octyl-3-methylimidazolium tetrafluoroborate (C<sub>8</sub>mimBF<sub>4</sub>) is examined in IL-rich regime using high-energy X-ray diffraction (HEXRD) and molecular dynamics (MD) simulations.
A quantum chemistry based, dipole polarizable force field has been used to simulate the N,N,N,N-tetramethylammonium (TMA) dicyanamide (DCA) ionic salt, in both plastic crystalline and liquid phases. Simulations predicted [TMA][DCA] crystal structure dimensions good agreement with experiment. Ion-counterion spatial distributions are understand local environment ion pairing of ions The rotational dynamics system thoroughly explored. Arrest DCA degrees freedom was associated experimentally...
Extensive atomistic molecular dynamics simulations have been employed to study the structure and orientational relaxation of azobenzene-based monolayers grafted a solid substrate. Systems with surface coverage 0.6 nm(2)/molecule were investigated over wide temperature range ranging from 298 K, where mesogens show local ordering monolayer was found be glassy, up 700 azobenzene groups nearly isotropic distribution, subnanosecond characteristic time scale. Biased that model single-molecule...
Simple tangent, hard site chains near a wall are modeled with density functional (DF) theory that uses the direct correlation function, c(r), as its “input.” Two aspects of this DF focused upon: (1) consequences variations in c(r)’s detailed form; and (2) correct way to introduce c(r) into formalism. The most important aspect is found be integrated value, ĉ(0). Indeed, it appears that, for fixed ĉ(0), all reasonable guesses shape result surprisingly similar distributions, ρ(r). Of course,...
The lithiation and delithiation of a silicon battery anode is modeled using the material point method (MPM). main challenges in modeling this process MPM to simulate stress dependent diffusion coupled with concentration within that undergoes large deformations. chosen as numerical choice because its ability handle A for described. model diffusivity three different constitutive models fully couple equations are considered. Verifications tests accuracy implementations validation experimental...
In a previous study of tangent hard-site chains near surface, the inhomogeneous density profiles were found through functional theory. current study, surface tensions these systems are from results thermodynamic integration. The calculated then compared to those directly computer simulation. Both tension and excess for polymeric shown differ qualitatively atomic systems, although certain similarities seen at high densities.