| In our first research project, silver core-vanadium/ferrous-doped titanium dioxide shell novel nanocomposite was synthesized to be used as an antibacterial agent. The results indicated that Ag core-0.1%V/Fe-doped TiO2 shell had the strongest antibacterial activity under lambdamax∼420 nm light source, which was three times as strong as that of well known antibacterial agent, Ag. V/Fe doped TiO2 did not show antibacterial activity under lambdamax∼ 394 nm and lambdamax∼500 nm light sources. However, it showed very mild inhibition under lambda max∼420 nm light source. The results also showed that insertion of the Ag core to V/Fe-doped TiO2 made it a strong antibacterial agent under the conditions used. Moreover, doping TiO2 shell of Ag core-TiO2 shell composite, with V/Fe, tremendously enhanced its antibacterial properties under visible light. Under the above-mentioned experimental conditions, Fe/V contributed to extend the photo responding range of TiO2 to visible light while Ag played a dominating role in charge separation. Therefore, this is an excellent method of overcoming two major drawbacks of TiO2 as a photocatalyst, namely low photo responding range and low quantum yield.;In our second project, we synthesized Polyvinylpyrrolidone (PVP) stabilized monodispersed crystalline nano zinc oxide (ZnO) and silica core-gold shell nanocomposite. Those nanomaterials were encapsulated in a water-based acrylic resin and dispersed in the emulsion using high shear force. Our emulsion was 100% transparent and the ZnO dispersed coating, cured on glass substrate, absorbed∼90% UV radiation while maintaining 80%-90% visible light transmittance with good adhesion to glass. Although the plasmon band of gold nanoshells was tuned as desired to NIR, the visible light transmittance was not satisfactory. However, that coating could have been utilized as a broadband filter. Therefore, two organic dyes, IR 806 and IR 165, were used in the emulsion to absorb NIR. IR 806 was employed with ZnO, but its narrow absorption band did not absorb NIR beyond 850 nm. Although water-insoluble stable IR 165 cannot be dispersed in water-based acrylic resin, it was well dispersed in the solvent-based resin Duramac. The cured coating on glass, poly carbonate (PC), and polymethylmethacrylate (PMMA) had good UV and NIR absorbance and visible light transmittance with good adhesion to substrate. Being cost effective and non-permanent, this kind of coating can be applied on any surface/object exposed to sunlight without adding considerable additional cost to whichever it is applied.;In our third project, we formulated a conductive coating by dispersing bimetallic Cu core-Ag shell (Cu Ag) nanocomposite in nonconductive acrylic polymers. Monometallic Cu, Ni, Ag and bimetallic Cu Ag, Ni Ag core-shell and Cu/Ag alloy nanocomposites were successfully synthesized. Morphologies of all monometallic and bimetallic nanoparticles/composites were spherical. TEM images clearly showed the Ag shell and Cu core of Cu Ag.;Although UV-visible spectra of Cu Ag and Cu/Ag alloy nanocomposites showed broader plasmon bands located between Cu and Ag plasmon bands, the plot of the wavelength of the maximum plasmon absorbance vs. the composition of the nanocomposites of different nanocomposites of varying Ag:Cu ratios followed completely opposite trends.;Conductivity of the Cu Ag nanocomposite dispersed emulsion depended on the metal loading. Cured coating of Cu Ag (Cu:Ag=1:3) nanocomposite dispersed in Water-based non-conductive acrylic emulsion (volume ratio emulsion: metal=1:1) showed conductivity in 20 kO range. These types of coatings, with improved conductivity, might be used on touch panels or cell phones for Electro Magnetic Radiation (EMR) shielding. (Abstract shortened by UMI.)... |
