Surface modification sensitization

In addition, there are many surface modification processes that use triplet sensitizers to permit oxidation reactions. In a typical process, polyisocyanate is applied on a polyolefin together with a sensitizer such as benzo-phenone and then irradiated with UV light. As shown in Eq. (15) the sensitizer has an oxidizing effect to produce hydroxyl groups over the polymer surface. These hydroxyl groups finally react with isocyanate to provide a functional polymer [56,57]. 

Hydrogenation is sensitive to the surface modifications. For example, the ball-milled powders require less activation compared to the conventional powders. For nanocrystalline hydrides, the grain boundary does not dramatically affect the PCI, which describes the thermodynamic aspects of hydride formation. However, the pressure for hydrogen desorption of the unmilled MgH2 is lower than that of the milled one as seen in Figure 11.7 [66]. 

The bonding of phosphonic acids to Si02 surfaces has also been reported in an organic solvent, Si-O-P bonds are formed by Si-OH/P-OH condensation [159] however, in an aqueous medium, no bonding was observed [127]. This behavior, which may be ascribed to the sensitivity of Si-O-P bonds to hydrolysis, has been utihzed for the micro- and nanopatterning of surfaces by selective surface modification of Ti02 patterns within a matrix ofSiOz [128]. 

Avseenko et al. (2001) immobilized antigens onto aluminum-coated Mylar films by electrospray (ES) deposition. Various surface modifications of the metallized films were studied to determine their abilities to enhance sensitivity. The plastic surfaces were firsf cleaned by plasma discharge treatment, followed by coating with proteins (BSA and casein) or polymers such as poly (methyl methacrylate) or oxidized dextran, or they were exposed to dichlorodimethyl silane to create hydrophobic surfaces. Protein antigen was prepared in 10-fold excess sucrose and sprayed onto the surfaces to form arrays with spot diameters between 7 and 15 pm containing 1 to 4 pg protein. 

In the preceding section, we emphasized that the surface interaction of metallic particles with liquid molecules is a very important parameter in the dispersion behavior of the sol. Since the surface nature is very sensitive to the surface modification, we can easily regulate it with the use of surfactant. As seen in Figure 9.4.23, almost all metallic particles cannot be dispersed in hexane as a suspension liquid. In this section, we show what kind of surfactant is effective in dispersion. The sample was prepared by the gas flow-cold trap method. We tested three surfactants, dimethyldi-... 

The development of electrodes to measure rapidly the concentration of ions to which they are uniquely sensitive has important applications in many fields. Two recent examples are quoted of surface modification of an electrode with a ligand showing some specificity for particular ions. 

Y. Yoshimi, T. Matsuda, Y. Itoh, F. Ogata and T. Katsube, Surface modifications of functional electrodes of a fight addressable potentiometric sensor (LAPS) non-dependency of pH sensitivity on the surface functional group, Mater. Sci. Eng. C, 5(2) (1997) 131-139. 

McCreery and co-workers have investigated the redox reactions for several redox analytes at glassy carbon electrodes, and have summarized the categorization of redox systems according to the effects of surface modification on electrode kinetics [1-3]. These redox analytes in the present study are known to be sensitive or insensitive to the electronic properties, surface microstructure, and surface termination of the carbon electrodes. 

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