The tunability of the chemical composition of ionic liquids (ILs), achieved by pairing various organic cations with numerous anions, allows for fine control of their physicochemical properties and ...has been widely used for the adjustment of the IL solvent characteristics. Exploitation of IL structural modularity coupled with chemical modification of the cation or anion to incorporate polymerizable groups is now an active area of research, resulting in the development of polymeric ionic liquids (poly(IL)s). The emergence of poly(IL)s as functional materials in the areas of polymer electrolytes, sorbents, dispersing agents, and nanomaterials is reviewed.
Transit through the carbon liquid phase has significant consequences for the subsequent formation of solid nanocarbon detonation products. We report dynamic measurements of liquid carbon condensation ...and solidification into nano-onions over ∽200 ns by analysis of time-resolved, small-angle X-ray scattering data acquired during detonation of a hydrogen-free explosive, DNTF (3,4-bis(3-nitrofurazan-4-yl)furoxan). Further, thermochemical modeling predicts a direct liquid to solid graphite phase transition for DNTF products ~200 ns post-detonation. Solid detonation products were collected and characterized by high-resolution electron microscopy to confirm the abundance of carbon nano-onions with an average diameter of ∽10 nm, matching the dynamic measurements. We analyze other carbon-rich explosives by similar methods to systematically explore different regions of the carbon phase diagram traversed during detonation. Our results suggest a potential pathway to the efficient production of carbon nano-onions, while offering insight into the phase transformation kinetics of liquid carbon under extreme pressures and temperatures.
Stimuli‐responsive supramolecular materials are of paramount importance for a broad range of applications. It is essential to impart versatility, sustainability, and scalability into these materials. ...Herein the authors report the design and synthesis of a new class of thermochromic supramolecular materials, which can easily be processed from water via a reversible sol–gel transition. The supramolecular materials are composed of a bis‐bipyridinium acceptor, a π‐electron‐rich naphthalene derivative donor, and halogen counterions. Long helical nanofibers can be assembled in water, gelating at room temperature. Inked designs, thin films, and aerogels are solution‐processed to exhibit thermochromic behavior based on competing π → π* and n → π* charge transfer interactions. By using different π‐electron rich donors, and counterions, the authors demonstrate that both the color observed at room temperature and at high temperatures can be tailored. The results open up the door to develop novel amphiphile‐based thermochromes with water processability and a large tunable color palette.
A new class of water‐processable thermochromic supramolecular materials has been developed. Inked designs, thin films, and aerogels fabricated from these composites exhibit reversible thermochromic behavior. The thermochromism is a result of competing π → π* and n → π* charge transfer interactions allowing for the color observed at room temperature and at high temperatures to be easily tailored.
Abstract
Benzene (C
6
H
6
), while stable under ambient conditions, can become chemically reactive at high pressures and temperatures, such as under shock loading conditions. Here, we report in situ ...x-ray diffraction and small angle x-ray scattering measurements of liquid benzene shocked to 55 GPa, capturing the morphology and crystalline structure of the shock-driven reaction products at nanosecond timescales. The shock-driven chemical reactions in benzene observed using coherent XFEL x-rays were a complex mixture of products composed of carbon and hydrocarbon allotropes. In contrast to the conventional description of diamond, methane and hydrogen formation, our present results indicate that benzene’s shock-driven reaction products consist of layered sheet-like hydrocarbon structures and nanosized carbon clusters with mixed
sp
2
-
sp
3
hybridized bonding. Implications of these findings range from guiding shock synthesis of novel compounds to the fundamentals of carbon transport in planetary physics.
Preparation and polymerization of a methylimidazolium-based ionic liquid (IL) that incorporates an acryloyl moiety at the terminus of a C8 alkyl chain is described. The IL monomer weakly ...self-assembles upon addition of water and oligomerizes on mild heating. Initiator-free polymerization (as evidenced by FT-IR spectroscopy) can be achieved by UV irradiation, forming an elastic, self-supporting hydrogel. Small-angle X-ray scattering (SAXS) studies on the unsupported polymer demonstrate that the hydrogel adopts an ordered lamellar structure. The polymer can absorb large quantities of water, swelling to nearly 200 times its original volume and, in the process, becoming a highly disordered lamellar structure. Swelling studies conducted using a range of organic solvents demonstrate that the polymer can also be swollen (albeit to a lesser extent) by polar, hydrogen-bonding solvents such as ethanol.
The surface functionalization of ultrananocrystalline diamond (UNCD) thin films via the electrochemical reduction of aryl diazonium cations is described. The one-electron-transfer reaction leads to ...the formation of solution-based aryl radicals, which in turn react with the UNCD surface forming stable covalent C−C bonds. Cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), ac impedance spectroscopy, and contact angle measurements have been employed to characterize the organic overlayer and estimate the surface coverage. The grafting of 3,5-dichlorophenyl groups renders the UNCD surface hydrophobic, whereas the attachment of 4-aminophenyl groups makes the surface relatively hydrophilic. The surface coverage, estimated from the electrochemical and XPS measurements, is as high as 70% of a compact monolayer. The aminophenyl terminated surface was obtained by electrochemical reduction of the tethered nitrophenyl groups. This two-step approach yields a UNCD surface with functional moieties available for the potential covalent coupling of a wide variety of biomolecules (e.g., DNA and proteins).
Pairing of a Keggin or Lindqvist polyoxometalate (POM) anion with an appropriate tetraalkylphosphonium cation is shown to yield the first members of a new family of ionic liquids (ILs). Detailed ...characterization of one of them, an ambient-temperature “liquid POM” comprising the Lindqvist salt of the trihexyl(tetradecyl) phosphonium cation, by voltammetry, viscometry, conductimetry, and thermal analysis indicates that it exhibits conductivity and viscosity comparable to those of the one previously described inorganic−organic POM-IL hybrid but with substantially improved thermal stability.
Glucose oxidase (GOx) adsorbed on an ionic liquid-derived polymer containing internally organized columns of Au nanoparticles exhibits direct electron transfer and bioelectrocatalytic properties ...towards the oxidation of glucose. The cationic poly(ionic liquid) provides an ideal substrate for the electrostatic immobilization of GOx. The encapsulated Au nanoparticles serve to both promote the direct electron transfer with the recessed enzyme redox centers and impart electronic conduction to the composite, allowing it to function as an electrode for electrochemical detection.
One-dimensional electron-density profiles derived from synchrotron small-angle X-ray scattering (SAXS) have been constructed and used to determine the conformational state of selected poly(ethylene ...oxide)−b-poly(propylene oxide)−b-poly(ethylene oxide) (PEO−PPO−PEO) triblock copolymers and the region of their association with a lipid bilayer. The number of molecular repeat units in the hydrophobic PPO block has been found to determine both the nature of triblock polymer−membrane association and the conformational state of the symmetric, flanking hydrophilic PEO units. For DMPC-based biomembranes, polymers whose PPO chain length is less than that of the bilayer thickness insert weakly into the membrane with the PEO blocks on the same side of the bilayer, leading to delocalization of the PEO at the membrane−water interface. This polymer architecture has been found not to alter the membrane fluidity and roughness. Conversely, polymers whose chain length is sufficient to span the lipid bilayer are tightly integrated, projecting their PEO chains into the water channels on opposing sides of the bilayer. The coiled conformational state of the PEO chains produces steric pressure on the bilayer, causing a thinning of the membrane and leading to a rigid, less-mobile bilayer than systems where the polymer is introduced as the lipid conjugate.
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