The mechanism and kinetics of interactions between dimethyl methylphosphonate (DMMP), a key chemical warfare agent (CWA) simulant, and Zr6-based metal organic frameworks (MOFs) have been investigated with in situ infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (PXRD), and DFT calculations. DMMP was found to adsorb molecularly to UiO-66 through the formation of hydrogen bonds between the phosphoryl oxygen and the free hydroxyl groups associated with Zr6 nodes on the surface of crystallites and not within the bulk MOF structure. Unlike UiO-66, the infrared spectra for UiO-67 and MOF-808, recorded during DMMP exposure, suggest that uptake occurs through both physisorption and chemisorption. The XPS spectra of MOF-808 zirconium 3d electrons reveal a charge redistribution following exposure to DMMP. In addition, analysis of the phosphorus 2p electrons following exposure and thermal annealing to 600 K indicates that two types of stable phosphorus-containing species exist within the MOF. DFT calculations, used to guide the IR band assignments and to help interpret the XPS features, suggest that uptake is driven by nucleophilic addition of an OH group to DMMP with subsequent elimination of a methoxy substituent to form strongly bound methyl methylphosphonic acid (MMPA). The rates of product formation indicate that there are likely two distinct uptake processes, requiring rate constants that differ by approximately an order of magnitude. However, the rates of molecular uptake were found to be nearly identical to the rates of reaction, which strongly suggests that the reaction rates are diffusion-limited. The final products were found to inhibit further reactions within the MOFs, and these products could not be thermally driven from the MOFs prior to decomposition of the MOFs themselves.

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The residual stress in a 6H-SiC wafer with a 3C-SiC epitaxial overlayer is determined by the technique of Synchrotron white beam x-ray topography (SWBXT). The short wavelength and high energy attributes of synchrotron radiation are exploited to very accurately determine the wafer curvature. Different approaches including absorption edge contour (AEC) mapping, multiple diffraction line (MDL) analysis and diffracted x-ray beam divergence (DXBD) analysis in both transmission and reflection geometry are demonstrated. The residual stress distribution is calculated from the wafer curvature measurement.

The fracture toughness of interface reinforced with dps-b-dpmma copolymer between immiscible polymers of PS and PMMA is tested by asymmetric double cantilever beam. The local deformation field at the interfacial crack tip is determined by the technique of SIEM. Normal and tangential crack opening displacements are calculated. A weak singularity is shown to exist near crack tip. Direct observation on the fracture process inside an environmental scanning electron microscope shows the large effect of mode mixity.