Characterization of sizing layers and buried polymer/sizing/substrate interfacial regions using a localized fluorescent probe

A novel technique is described to investigate buried polymer/sizing/substrate interfacial regions, in situ, by localizing a fluorescent probe molecule in the sizing layer. Epoxy functional silane coupling agent multilayers were deposited on glass microscope cover slips and doped with small levels of a fluorescently labeled silane coupling agent (FLSCA). The emission of the grafted FLSCA was dependent on the silane layer thickness, showing blue-shifted emission with decreasing thickness. The fluorescent results suggest that thinner layers were more tightly bound to the glass surface. The layers were also characterized by scanning electron microscopy, contact angle, and thermogravimetric analysis (TGA). When the FLSCA-doped silane layers were immersed in epoxy resin, a blue shift in emission occurred during resin cure, indicating the potential to study interfacial chemistry, in situ. Thicker silane layers exhibited smaller fluorescence shifts during cure, suggesting incomplete resin penetration into the thickest silane layers.     

ON THE COMPUTATIONAL COMPLEXITY OF THE MAXIMUM TRADE PROBLEM

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联苯胺分光光度法测定食盐中碘含量

基于在盐酸介质中,碘酸钾氧化联苯胺使其显色,提出了光度法测定食盐中微量碘的方法。在40℃的水浴中,当2 mol.L-1盐酸溶液用量为1.00 mL0、.42 g.L-1联苯胺溶液用量为0.80 mL时,方法的线性范围为100~1 400μg.L-1,最大吸收波长在425 nm处,表观摩尔吸光率为1.4×105L.mol-1.cm-1。用于测定加碘食盐中碘含量的测定,回收率在97.5%~101.2%之间,相对标准偏差(n=7)在0.9%~1.9%之间。     

Interpreting the signal from a localized fluorescence sensor: a study by angle-resolved XPS and dynamic SIMS

Angle-resolved X-ray photoelectron spectroscopy (XPS) and dynamic secondary ion mass spectroscopy (DSIMS) experiments were conducted to assess the interactions between a diamine curing agent and a glycidoxysilane-modified glass substrate. This effort was motivated by earlier work, in which a fluorescent probe localized in dilute quantities in the silane layer was used to track the penetration of the resin into the silane layer, as well as the resin cure. XPS and DSIMS experiments were performed on the silane layers immersed only in the resin hardener, providing more detailed information about the concentration profile and structural reorganization within the silane layer due specifically to hardener penetration. Dynamic SIMS spectra reveal the presence of hardener in the layer, as indicated by the strong CN- signal throughout the silane layer thickness. The XPS results indicate the presence of an amine gradient within the top 10 nm of the silane coating, with less amine penetration deeper into the silane layer. The XPS data also suggest some level of anisotropy in the molecular structure of the diamine/glycidoxysilane coating, as revealed by the differences in the relative atomic concentrations and peak positions of the C1s components at two different take-off angles.