Nanoparticle-Doped Materials

The field of liquid crystal nanoscience has experienced tremendous growth over the past decade. Research on nanoparticle-doped liquid crystals makes use of a wide variety of nanoparticles differing in size, shape, core material, and coating (Fig. 23). 

Another method for measuring thermal diffusivity is the flash method developed by Parker et al. [48] and successfully used for the thermal diffusivity measurement of solid materials [49]. A high intensity short duration heat pulse is absorbed in the front surface of a thermally insulated sample of a few millimeters thick. The sample is coated with absorbing black paint if the sample is transparent to the heat pulse. The resulting temperature of the rear surface is measured by a thermocouple or infrared detector, as a function of time and is recorded either by an oscilloscope or a computer having a data acquisition system. The thermal diffusivity is calculated from this time-temperature curve and the thickness of the sample. This method is commercialized now, and there are ready made apparatus with sample holders for fluids. There is only one publication on nanofluids with this method. Shaikh et al. [50] measured thermal conductivity of carbon nanoparticle doped PAO oil. 

Fig. 14 Series of in-situ GISAXS images of a cylindrical nanoparticle-doped PS- >-P2VP film during thermal annealing at 180°C (a) 0 h, (b) 4 h, and (c) 14 h after spin coating. Reprinted with permission from Advanced Materials [86]. Copyright (2007) Wiley-VCH...

Metal nanoparticle-doped sol-gel silica nanocomposites do not possess the required conductivity to fabricate bulk or screen-printed electrodes. Inspired by the well-known resorcinol/formaldehyde sol-gel process, which can be pyro-lyzed to get a conductive amorphous carbon matrix, we have synthesized a nanocomposite material made of a carbon xerogel doped with bismuth nanoparticles and fabricated a carbon paste electrode for heavy metal analysis (Figure 46.11) [24]. The resulting sensor is very sensitive to several heavy metals. Extremely low detection limits for Pb " and Cd of around 0.5 ppb were achieved using a nanocomposite paste electrode containing 6 wt. % of bismuth. 

Nanoclusters/Polymer Composites. The principle for developing a new class of photoconductive materials, consisting of charge-transporting polymers such as PVK doped with semiconductor nanoclusters, sometimes called nanoparticles, Q-particles, or quantum dots, has been demonstrated (26,27). 

Oluwafemi, O. S. Revaprasadu N and Adeyemi O. O. (2010). A new synthesis of hexadecylamine-capped Mn-doped wurtzite CdSe nanoparticles. Material Letter, 64, 1513-1516. 

Nanoparticles of Mn and Pr-doped ZnS and CdS-ZnS were synthesized by wrt chemical method and inverse micelle method. Physical and fluorescent properties wra cbaractmzed by X-ray diffraction (XRD) and photoluminescence (PL). ZnS nanopatlicles aniKaled optically in air shows higher PL intensity than in vacuum. PL intensity of Mn and Pr-doped ZnS nanoparticles was enhanced by the photo-oxidation and the diffusion of luminescent ion. The prepared CdS nanoparticles show cubic or hexagonal phase, depending on synthesis conditions. Core-shell nanoparticles rahanced PL intensity by passivation. The interfacial state between CdS core and shell material was unchan d by different surface treatment. 

Li, Q., Li, Y.W., Wu, P., Xie, R., and Shang, J.K. (2008) Palladium oxide nanoparticles on nitrogen-doped titanium oxide accelerated photocatalytic disinfection and post-illumination catalytic memory . Advanced Materials, 20 (19), 3717-3723. 

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