Nanocomposites particles

Bhandarkar, S. and Bose, A. (1990) Synthesis of nanocomposite particles by intravesicular coprecipitation. Journal of Colloid and Interface Science, 139, 541-550. 

Fig. 2.2.8 Preparation of CdS (dispersed quantum dot)/SiO nanocomposite particles. (From Refs. 35-37.)...

Fig. 6 Cryo-TEM images of the silver nanocomposite particles prepared using PS-PNIPA particles with different crosslinker content (a) KPSl-Ag (2.5 mol% BIS), (b) KPS2-Ag (5mol% BIS), and (c) KPS3-Ag (10mol% BIS), (d) Influence of degree of crosslinking on the morphology of silver composite particles [60]...

The kinetics of 4-nitrophenol reduction in presence of microgel-metal nanocomposite particles was studied by UV/Vis spectroscopy. Figure 9 shows the UV spectra for the reduction of 4-nitrophenol measured at different times. For a typical measurement, successive decrease of peak intensity at 400 nm with time can be utilized to obtain the rate constant [59, 72, 73]. This peak is attributed due to the presence of 4-nitrophenate ions in the system. The formation of 4-nitrophenate ions... 

Fig. 13 Test reaction (oxidation of benzyl alcohol to benzaldehyde) used for the analysis of the catalytic activity of microgel-metal nanocomposite particles. All runs were done at room temperature...

Metal nanoparticles embedded in thermosensitive core-shell microgel particles can also work efficiently as catalyst for this reaction. Figure 13 shows the oxidation reaction of benzyl alcohol to benzaldehyde in aqueous media by using microgel-metal nanocomposite particles as catalyst. All reactions were carried out at room temperature using aerobic conditions. It is worth noting that the reaction conditions are very mild and no phase transfer catalyst is needed. It has been found that microgel-metal nanocomposites efficiently catalyze the aerobic oxidation of benzyl alcohol at room temperature. No byproducts have been detected by GC after the reaction, and water is the only product formed besides the aldehyde. 

Figure 15 shows the influence of temperature on the catalytic activity in an Arrhenius plot of the TOFs. These data can be compared to data obtained for the reduction of 4-nitrophenol with an excess of NaBkLt in presence of the metal nanocomposite particles. From Fig. 15, a nonlinear relationship between In (TOF) and T l can be seen. The TOF increase more than exponentially with increased temperature. Only in the immediate vicinity a significantly smaller TOF is monitored. 

Fig. 15 TOF (squares) and hydrodynamic radius (circles) versus 1 IT for the oxidation of benzyl alcohol in the presence of microgel-Au nanocomposite particles (1 atm air, 1 mmol K2CO3, [microgel-Au] = 3.68 x 10 5 molL-1). The lines are guides for the eye [29]...

Lu Y, Yu M, Drechsler M, Ballauff M (2007) Ag nanocomposite particles preparation, characerization and application. Macromol Symp 254 94-102... 

Figure 16.17 shows the formation of conductive polymer/inor-ganic oxide nanocomposite particles. Silica, having a particle size of 20 nm, was dispersed in water, oxidant was added, followed by addition of monomer (pyrrole or aniline), and polymerization was conducted under constant stirring for 16 h at room temperature. Raspberry clusters of nanocomposite were ob-tained. ... 

Chen, T.Y. and Somasundaran, R, Preparation of novel core-shell nanocomposite particles by controlled polymer bridging, J. Am. Ceram. Soc., 81, 140, 1998. 

The polymer-clay nanocomposites were synthesized by exfoliating a known amount of clay in water and then mixing this with a very small amount of polymer. Nanocomposite particles flocculated from the solution within 1-2 h. The mixture was stirred for 12-24 h and the nanocomposites were isolated by centrifugation followed by washing and drying for at least 24 h in vacuo. 

Armes et al. contended in recent studies [49,50,55,96,97] that the PANI and PPY colloidal silica based nanocomposite particles were characterized by a typ-... 

Wang, D., He, J., Rosenzweig, N. and Rosenzweig, Z. (2004) Superparamagnetic Fe203 beads-CdSe/ZnS quantum dots core-shell nanocomposite particles for cell separation. Nano Lett., 4, 409—413. 

It is not clear why nanocomposite particles weaken wood flour- and rice-hulls-filled polypropylene, but it seems to be a repetitive and reproducible phenomenon. Certainly, it can be hypothesized that the reason is the nonuniform dispersion of cellulose fillers and nanoclay particles, but it remains just a hypothesis. 

Indium-tin oxide (ITO) glasses have also been used as support for NS-TiOz [464-467]. For instance, Peralta-Hernandez et al. [464] reported deposition of T /02-carbon nanocomposite on ITO glass plates by electrophoretic deposition (ED) method. ITO glass plates were immersed in 10 mL of a colloidal suspension of ri02-carbon nanocomposite particles. Accordingly, a 4 V potential difference was applied between a stainless steel shield and the negative ITO plate for a period of 40 s at room temperature. The distance between the electrodes was 2 cm. Fresh electrodes were placed in an oven to sinter the nanocomposite film in the air at 450°C for 30 min. Photocatalytic activity of prepared electrodes were tested for removal of Orange II [464]. 

Since the late 1980s several innovative syntheses of polypyrroles have been discovered. The photosensitized polymerization of pyrrole in aqueous solution and in polymer matrices using tris(2,2 -bipyridine)ruthenium(II) as a photosensitizer has been reported <89CC132>, and PPy can be photochemically deposited on to any type of surface under visible light irradiation conditions <89CC657, 90CC387). The preparation and potential applications of surface-functionalized polypyrrole-silica nanocomposite particles have been discussed <94PP217>. 

Zhang JJ, Gao G, Zhang M, et al. (2006) ZnO/PS core-shell hybrid microspheres prepared with miniemulsion polymerization. J Colloid Interface Sci 301 78-84 Mahdavian A, Stirrafi Y, Shabankareh M (2009) Nanocomposite particles with core-shell morphology. 111. Preparation and characterization of nano Al203-poly(styrene-methyl methacrylate) ptirticles via miniemulsion polymerization. Polym Bull 63 329-340... 

Zhang SW, Zhou SX, Weng YM, et al. (2005) Synthesis of Si02/polystyiene nanocomposite particles via miniemulsion polymerization. Langmuir 21 2124-2128... 

Qi DM, Bao YZ, Weng ZX, et al. (2006) Preparation of acrylate polymer/sUica nanocomposite particles with high sdlica encapsulation efficiency via miniemulsion polymerization. Polymer 47 4622-4629... 

Qiang W, Wang Y, He P, et al. (2008) Synthesis of asymmetric inoiganic/polymer nanocomposite particles vialocalized substrate surface modification and miniemulsion polymerization. Langmuir 24 606-608... 

BaUly B, Donnenwitth AC, Bartholome C, et td. (2006) Silica-polystyrene nanocomposite particles synthesized by nitroxide-mediated polymerization and their encapsulation through miniemulsion polymerization. J Nanomater 2006 1—10... 

Mirzataheri M, Mahdavian A, Atai M (2009) Nanocomposite particles with core-shell morphology IV an efficient approach to the encapsulation of Cloisite 30B by poly (styrene-co-butyl acrylate) and preparation of its nanocomposite latex via miniemulsion polymerization. Colloid Polym Sd 287 725-732... 

Mahdavian AR, Sehri Y, Salehi-Mobarakeh H (2008) Nanocomposite particles with core-sheU morphology. 11. An investigation into the affecting parameters on preparation of Fc3 04-poly (butyl acrylate-styrene) particles via miniemulsion polymerization. Eur Polym J 44 2482-2488... 

Percy and coworkers [39,40] synthesized colloidal dispersions of polymer-silica nanocomposite particles by homopolymerizing 4-vinylpyridine or copolymerizing 4-vinylpyridine with either methyl methacrylate, styrene, n-butyl acrylate or n-butyl methacrylate in the presence of fine-particle silica sols using a free-radical in aqueous media at 60°C. No surfactants were used and a strong acid-based interaction was assumed to be a prerequisite for nanocomposite formation. The nanocomposite particles had comparatively narrow size distributions with mean particle diameters of 150-250 nm and silica contents between 8 and 54 wt.%. The colloidal dispersions were stable at solids contents above 20 wt.%. 

Percy and Aimes [41] showed that poly (methyl metha-crylate)-sihca nanocomposite particles can be readily prepared in aqueous alcoholic media at around ambient temperature without using either auxiliary comonomers such as 4-vinylpyridine or surfactants. In this work the silica sol was an organosol of 20 nm silica particles in isopropyl alcohol with a solids content of 30 wt.%. 

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