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Zirconium hydroxide was evaluated for the ability to detoxify chemical warfare agents GD, HD, and VX. Observed half-lives were 8.7 min, 2.3 h, and 1 min, respectively. Owing to its extremely fast reaction rate, the mechanism for VX was further characterized. Zirconium hydroxide samples were calcined at temperatures ranging from 150 to 900 °C to investigate the effect of surface speciation on VX hydrolysis rates. NMR, TGA/DSC, TEM, and potentiometric tritration reveal the importance of the acidic, bridging OH groups of Zr(OH)4 which are proposed to protonate and catalytically hydrolyze VX in a manner similar to autocatalysis by EMPA in solution.

Zirconium hydroxide (Zr(OH)4) is a catalytic support material whose reactivity depends on intrinsic surface hydroxyl groups. Here we present a 1H MAS NMR study where we identify bridging and terminal hydroxyl groups along with their concentrations even in completely dehydrated material. The dehydrated material contains 13 mmol/g bridging hydroxyl groups and 3.9 mmol/g terminal hydroxyl groups, yielding a ratio of 3.4:1, and is verified by XPS. Upon hydration, the number of surface hydroxyl groups remains constant while only bulk water is adsorbed on the surface. Knowing both the types and amounts of surface hydroxyl groups on Zr(OH)4 helps explain the catalytic activity of Zr(OH)4 in many applications.

Using 31P and 13C NMR with DFT calculations we demonstrate the exposed surface of titania nanotubes (TiNTs) is a stable, unterminated anatase (0 0 1)-like surface and is catalytically active under ambient conditions. We find that methanol dissociatively adsorbs on the surface of TiNTs agreeing with the predicted activity of surface dissociation of organic molecules on the crystalline (0 0 1)-anatase surface. We further examined the catalytic activity of anatase power, TiNT, and nanosheets in catalytic hydrolysis of S-[2-(diisopropylamino)ethyl]-O-ethyl methylphosphonothioate (VX) via 31P NMR and demonstrate that titanate-like nanosheets are inactive in the reaction owing to their hydroxylated (0 0 1) surface.

A unique atomic force microscope-based local thermal-mechanical analysis (LTA) technique was used to study the influence of room temperature aging on viscoelastic properties of ethylene-methacrylic (E/MAA) acid ionomers. This approach permits easy access to structural relaxation effects on viscoelasticity at a short aging time, for instance, before the occurrence of secondary crystallization differential scanning calorimetry (DSC) melting peak. A Burger model along with finite element method yields quantitative analysis of viscoelastic properties versus the aging time. Creep curves were obtained with LTA after various times of aging at room temperature upon cooling from the melt. Measurements were carried out at both 30 and 70 °C. The results reveal the effects of structural relaxation upon aging in the ion-rich amorphous region, the influence of secondary crystallites on the viscoelastic properties, and shed light on the processes associated with aging in E/MAA ionomers.

Molecule immobilization in hydrothermally synthesized titania nanotubes is investigated by 13C solid-state NMR aided density functional theory calculations. The changes of 13C NMR spectra before and after immobilization indicate that phenols are chemisorbed and that aliphatic acid is possibly physisorbed in titania nanotubes. Hydroquinone exhibits monodentate bonds, and catechol exhibits bidentate bonds to accessible surface Ti sites in titania nanotubes. Immobilization of anthrarobin confirms that bidentate bonding is favored over monodentate bonding. Density functional calculations at the B3LYP/6-311+G(2d,p) level suggest that catechol is immobilized dissociatively via bridge bidentate bonding to neighboring surface Ti sites rather than chelate bidentate bonding to single surface Ti sites.

We constructed a truly nanotubular structure model of titania nanotubes based on delaminated anatase with realistic dimensions replicating those observed in experiments. It is shown that this nanotubular structure based on delaminated anatase produces an XRD pattern in excellent agreement with the observed spectrum and that the tube axis is along the [0 1 0] direction of the anatase structure. Preserving the atomic registry of delaminated anatase between adjacent layers is essential along the tube axis but unnecessary along the circumference. These understandings provide detailed information on the structure and morphology of hydrothermally synthesized titania nanotubes. The findings will help discern the complex surface chemistry of these materials.

Water confinement within single-walled carbon nanotubes (SWCNTs) has been a topic of current interest, due in part to their potential nanofiltration applications. Experiments have recently validated molecular dynamics predictions of flow enhancement within these channels, although few studies have probed the detailed structure and dynamics of water in these systems. Proton nuclear magnetic resonance ( (1)H NMR) is a technique capable of providing some of these details, although care must be exercised in separating the confined water of interest from exterior water. By using controlled experiments with both sealed and opened SWCNTs and by providing a quantitative measure of water content through desorption experiments, a signature for confined water in SWCNTs has been positively identified. This endohedral or interior water is characterized by a relatively broad feature located at 0.0 ppm, shifted upfield relative to bulk water. With the identification of a signature for water inside SWCNTs, further studies aimed at probing water dynamics will be enabled.

Anatase, viewed traditionally as a three-dimensional TiO2 structure, has major applications in solar cells, hydrogen production, and catalysis. Here, we report the synthesis, characterization, and structural simulation of a layered nanosheet material that can be described as delaminated anatase along the [001] direction. Counting the outer and interlayer surfaces, such a nanosheet structure maximizes the areas of surfaces which are similar to anatase (001), believed to be the surface of central importance for the superior efficiency of anatase in various applications. Indeed, the important dissociative adsorption process of water predicted to occur on the anatase (001) surface is observed in such nanosheet material. It is also shown that the structure of titania nanotubes, an issue of debate for nearly a decade, can also be described by delaminated anatase along the [001] direction. Interestingly, the strains in such a curved tubular structure lead to major differences in surface chemistry such as water d...

13 C NMR is employed to study the correlation between molecular dynamics and melting transition for the bulk ibuprofen and the confined ibuprofen in titania nanotubes. Under confinement, for all methyl-groups rotation remains unchanged and aromatic-ring flipping is slightly accelerated. The bulk ibuprofen melts at 351 K activating rapid molecular reorientation and rapid rotation of isobutyl-group while the confined ibuprofen completely becomes ‘liquid-like’ at 339 K activating also rapid rotation of isobutyl-group and restricted molecular reorientation. It suggests that confinement substantially changes the segmental dynamics which participates in melting transition but only slightly affects the others.

This work employs two-dimensional solid-state NMR methods to uncover the structure and molecular arrangement of physically trapped stearic acid (SA) inside a titanate nanotube (TiNT). Thermal annealing the mixture of SA and the water-washed TiNT is shown to induce slow physical trapping of SA into the TiNT. In contrast to that the solid-state bulk exhibits only one carbonyl 13C peak of NMR and consists solely of dimer, the physically trapped SA exhibits two carbonyl 13C peaks with different chemical shifts that are assigned respectively to dimer and monomer both by the 13C homonuclear double-quantum measurement and by the 13C chemical-shift-tensor measurement. The trapped SA monomer and dimer are shown to grow simultaneously during thermal annealing with a constant number ratio between them at ∼1:1. The 13C homonuclear double-quantum and the 1H−13C HETCOR spectra indicate that the trapped SA monomer and dimer do not form separated clusters but are neighbors to each other. As such, the trapped SA in the Ti...

Raman spectroscopy is an analytical technique with vast applications in the homeland security and defense arenas. The Raman effect is defined by the inelastic interaction of the incident laser with the analyte molecule’s vibrational modes, which can be exploited to detect and identify chemicals in various environments and for the detection of hazards in the field, at checkpoints, or in a forensic laboratory with no contact with the substance. A major source of error that overwhelms the Raman signal is fluorescence caused by the background and the sample matrix. Novel methods are being developed to enhance the Raman signal’s sensitivity and to reduce the effects of fluorescence by altering how the hazard material interacts with its environment and the incident laser. Basic Raman techniques applicable to homeland security applications include conventional (off-resonance) Raman spectroscopy, surface-enhanced Raman spectroscopy (SERS), resonance Raman spectroscopy, and spatially or temporally offset Raman spectroscopy (SORS and TORS). Additional emerging Raman techniques, including remote Raman detection, Raman imaging, and Heterodyne imaging, are being developed to further enhance the Raman signal, mitigate fluorescence effects, and monitor hazards at a distance for use in homeland security and defense applications.

A novel technique for determining the relative accessibility and reactivity of basic surface hydroxyl sites by reacting various zirconium(IV) hydroxide materials with 2,2,2-trifluoroethanol (TFE) and characterizing the resulting material using (19)F magic angle spinning (MAS) nuclear magnetic resonance (NMR) is presented here. Studied here are three zirconium hydroxide samples, two unperturbed commercial materials, and one commercial material that is crushed by a pellet press. Factors, such as the ratio of bridging/terminal hydroxyls, surface area, and pore size distribution, are examined and found to affect the ability of the zirconium(IV) hydroxide to react with TFE. X-ray diffraction, nitrogen isotherms, and (1)H MAS NMR were used to characterize the unperturbed materials, while thermogravitric analysis with gas chromatography and mass spectrometry along with the (19)F MAS NMR were used to characterize the materials that were reacted with TFE. Zirconium hydroxide materials with a high surface area and a low bridging/terminal hydroxyl ratio were found to react TFE in the greatest amounts.

Self-healing ability is a fascinating property of some materials. Structural materials with self-healing ability require a subtle combination of flow and stiffness characteristics. A vivid demonstration of self-healing is the automatic sealing of the bullet hole after bullet penetration of the target material. The ionomer Surlyn® satisfies the needs of both structural requirements and self-healing to a certain extent. The viscosity of Surlyn is very high at room temperature, a favorable property for structural applications but unfavorable for self-healing. However, when it was heated to 100°C and then cooled back down to room temperature, its viscosity remains temporarily low at room temperature for a few minutes, a favorable condition for healing. Here we report the measurement of such short-time relaxation effects on flow properties in Surlyn using an atomic force microscope (AFM)-based local thermal mechanical analyzer (LTA).

(1) In abstract, last sentence contains a spelling error of word ‘powder’. Should read ‘. . .further examined the catalytic activity of anatase powder. . .’ (2) Nomenclature errors exist in the article on Page 4, in Section 3.2. ‘Catalytic hydrolysis of VX’ that require correction. The anatase powder used in our VX decontamination experiments is referred to as ‘nanocrystals’ and ‘nanoparticles’ in that section of the article.