A5047369734- Polymer Nanocomposites and Properties
- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Polymer crystallization and properties
- Carbon Dioxide Capture Technologies
- Carbon dioxide utilization in catalysis
- Membrane Separation and Gas Transport
- Metal-Organic Frameworks: Synthesis and Applications
- Advanced Physical and Chemical Molecular Interactions
- Phase Equilibria and Thermodynamics
- Material Dynamics and Properties
- Fiber-reinforced polymer composites
- Conducting polymers and applications
- biodegradable polymer synthesis and properties
- Advanced Polymer Synthesis and Characterization
- Surfactants and Colloidal Systems
- Covalent Organic Framework Applications
- Carbon Nanotubes in Composites
- Supercapacitor Materials and Fabrication
- Trauma, Hemostasis, Coagulopathy, Resuscitation
- Environmental Engineering and Cultural Studies
- Metal Extraction and Bioleaching
- Rheology and Fluid Dynamics Studies
- Inorganic and Organometallic Chemistry
- Nanomaterials for catalytic reactions
Oak Ridge National Laboratory
2017-2022
University of Tennessee at Knoxville
2016-2020
Joint Institute for Computational Sciences
2020
Knoxville College
2017-2018
University of Tübingen
2002
Cornell University
1989
Polymer nanocomposites (PNCs) are important materials that widely used in many current technologies and potentially have broader applications the future due to their excellent property tunability, light weight, low cost. However, expanding limits enhancement remains a fundamental scientific challenge. Here, we demonstrate well-dispersed, small (diameter ∼1.8 nm) nanoparticles with attractive interactions lead unexpectedly large qualitatively different changes PNC structural dynamics...
It is generally believed that the strength of polymer–nanoparticle interaction controls modification near-interface segmental mobility in polymer nanocomposites (PNCs). However, little known about effect covalent bonding on dynamics and glass transition matrix-free polymer-grafted nanoparticles (PGNs), especially when compared to PNCs. In this article, we directly compare static dynamic properties poly(2-vinylpyridine)/silica-based with chains either physically adsorbed (PNCs) or covalently...
The mechanical reinforcement of polymer nanocomposites (PNCs) above the glass transition temperature, Tg, has been extensively studied. However, not much is known about origin this effect below Tg. In Letter, we unravel mechanism PNC within glassy state by directly probing nanoscale properties with atomic force microscopy and macroscopic Brillouin light scattering. Our results unambiguously show that "glassy" Young's modulus in interfacial layer PNCs two-times higher than bulk polymer, which...
The thickness of the interfacial layer between a nanoparticle and surrounding polymer matrix is experimentally shown to decrease in as chain length increases, contrasting theoretical predictions.
While it is known that the properties of polymer nanocomposites are largely dominated by interfacial layer around nanoparticles, molecular parameters controlling structure and dynamics remain unknown. In this work we combine small-angle X-ray scattering, differential scanning calorimetry, broadband dielectric spectroscopy to analyze dependence thickness, lint, on rigidity defined through characteristic ratio, C∞. This analysis revealed a value C∞ ∼ 5–7, beyond which lint increases...
We report a bench-scale direct air capture (DAC) process comprising CO2 absorption with aqueous amino acid salts (i.e., potassium glycinate, sarcosinate), followed by room-temperature regeneration of the acids reaction solid meta-benzene-bis(iminoguanidine) (m-BBIG), resulting in crystallization hydrated m-BBIG carbonate salt, (m-BBIGH2)(CO3)(H2O)n (n = 3–4). The is subsequently released mild heating (60–120 °C) crystals, which regenerates quantitatively. This low-temperature...
The structure and polymer-nanoparticle interactions among physically adsorbed poly(2-vinylpyridine) chains on the surface of silica nanoparticles (NPs) were systematically studied as a function molecular weight (MW) by sum frequency generation (SFG) X-ray photoelectron (XPS) spectroscopies. Analysis XPS data identified hydrogen bonds between polymer NPs, while SFG evaluated change in number free OH sites NP's surface. Our revealed that amount -OH have significant dependence polymer's MW....
Abstract Direct air capture (DAC) technologies that extract carbon dioxide from the atmosphere via chemical processes have potential to restore atmospheric CO 2 concentration an optimal level. This study elucidates structure‐property relationships in DAC by crystallization of bis(iminoguanidine) (BIG) carbonate salts. Their crystal structures are analyzed X‐ray and neutron diffraction accurately measure key structural parameters including molecular conformations, hydrogen bonding,...
Synthetic control of soft nanoparticles provides a conduit to thoroughly investigate the correlation nanoscale structure particle and nanocomposite properties.
SANS provides, for the first time, unique insight into correlation between organic radical polymer molecular structure and their assembly.
The dynamics of polymers in an all-polymer nanocomposite that are composed soft cross-linked polystyrene nanoparticles and linear have been investigated. In this article, we describe how the relative size nanoparticle to polymer chain its rigidity impact diffusion. results situ neutron reflectivity experiments show three distinct regimes indicate inclusion increases amount topological constraints confinement effects for low matrix molecular weight polymer. At modest weights where similar,...
We present a novel elastomer with an amphiphilic triblock/graft architecture, allowing it to rapidly swell in water and form tough hydrogel. The design was motivated by uncontrolled hemorrhage, responsible for 80–90% of potentially survivable deaths US soldiers over the past 15 years. polymer is 5.7 times as absorbent 3 state art gauze-based hemostatic dressing. It swells equilibrium within seconds phosphate buffered saline due microphase-separated morphology featuring continuous mobile...
The production of high-strength carbon fibers is an energy-intensive process, where a significant cost involves the wet or dry-spinning polyacrylonitrile (PAN) fiber precursors. Melt-spinning PAN would allow for reduction in and hazards. Ionic liquids (ILs) are attractive fiber-processing medium because their negligible vapor pressure low toxicity. In addition, they carbon-forming precursors; upon carbonization, residual ILs can enhance yield, although primarily useful plasticized...
We report a structure-properties relationship study of DAC by crystallization bis-iminoguanidine (BIG) carbonate salts. The focuses on series basic BIG structures including the glyoxal-bis(iminoguanidine) prototype (GBIG) and its simple analogs methylglyoxal-bis(iminoguanidine) (MGBIG) diacetyl-bis(iminoguanidine) (DABIG). find that minor structural modifications in molecular structure GBIG, such as substituting one or two hydrogen atoms with methyl groups, result major changes crystal...
As the predominant precursor for high-performance carbon fiber manufacturing, fabrication of polyacrylonitrile (PAN)-based composite fibers attracts great interest. Ionic liquids (ILs) have recently been investigated melt-spinning ultrafine PAN fibers. The plasticizing properties ILs are significantly affected by structure and can be influenced electronegativity, steric effects, etc. Herein, we report a facile strategy to control elasticity PAN/ILs tuning anion ILs. Particularly, containing...
A bench-scale direct air capture process is reported, based on CO2 absorption with aqueous amino acids and carbonate crystallization a guanidine compound.
A bench-scale direct air capture process is reported, based on CO2 absorption with aqueous amino acids and carbonate crystallization a guanidine compound.