Nanoparticles stabilization

FIG. 13 Langmuir-Blodgett films of dioctadecyldimethylammonium bromide incorporating 6.0-nm-diameter CdS nanoparticles stabilized by 0.2 mM sodium hexametaphosphate. (a) Absorbance spectra for 2, 3, 4, 5, 6, 7, 8, and 13 layers (bottom to top) the inset shows the linearity of the absorbance at 450 nm versus the number of layers, (b) Fluorescence spectra (excitation wavelength = 400 nm) for 2, 3, 4, 6, 8, 13, and 18 layers (bottom to top) the inset shows the emission intensity at 480 nm versus the number of layers. (Reproduced with permission from Ref. 152. Copyright 1994 American Chemical Society.)... 

In this section, a description of the experimental procedure used to prepare and characterize metal nanoclusters stabilized by DMAA-based microgels (M5, MIO, M20) is provided. Details of the experimental procedure used to prepare nanoparticles stabilized by MMA-based microgels have been reported elsewhere [13b]. 

In the early work on the thermolysis of metal complexes for the synthesis of metal nanoparticles, the precursor carbonyl complex of transition metals, e.g., Co2(CO)8, in organic solvent functions as a metal source of nanoparticles and thermally decomposes in the presence of various polymers to afford polymer-protected metal nanoparticles under relatively mild conditions [1-3]. Particle sizes depend on the kind of polymers, ranging from 5 to >100 nm. The particle size distribution sometimes became wide. Other cobalt, iron [4], nickel [5], rhodium, iridium, rutheniuim, osmium, palladium, and platinum nanoparticles stabilized by polymers have been prepared by similar thermolysis procedures. Besides carbonyl complexes, palladium acetate, palladium acetylacetonate, and platinum acetylac-etonate were also used as a precursor complex in organic solvents like methyl-wo-butylketone [6-9]. These results proposed facile preparative method of metal nanoparticles. However, it may be considered that the size-regulated preparation of metal nanoparticles by thermolysis procedure should be conducted under the limited condition. 

Scheme 1. The solvent-free controlled thermolysis of gold(I) thiolate complex producing gold nanoparticles stabilized by alkyl groups derived from the precursor.

Gold nanoparticles stabilized by primary amine, tertiary amine, sulfide, and thiols... 

Scheme 2. Production of size-regulated gold nanoparticles stabilized by primary amines, tertiary amines, sulfides, and thiols formed by the controlled thermolysis of gold(I) thiolate complex in the presence of amine (reprinted from Ref. [11], 2005, with permission from Elsevier).

Figure 5. High-resolution SEM images of the Si surface covalently linked to the nanoparticles stabilized by (A) C3, (B) C6, and (C) Cll. (Reprinted with permission from Ref [11a], 2004, American Chemical Society.)...

Haas I, Shanmugam S, Gedanken A (2006) Pulsed sonoelectrochemical synthesis of size-controlled copper nanoparticles stabilize by poly(N-vinylpyrrolidone). J Phys Chem B 110 16947-16952... 

S8 Paknikar, KM., Nagpal, V., Pethkar, A.V. and Rajwade, J.M. (2005) Degradation of lindane from aqueous solutions using iron sulfide nanoparticles stabilized by biopolymers. Science and Technology of Advanced Materials, 6, 370-374. 

J.J. Feng, G. Zhao, J.J. Xu, and H.Y. Chen, Direct electrochemistry and electrocatalysis of heme proteins immobilized on gold nanoparticles stabilized by chitosan. Anal. Biochem. 342, 280-286 (2005). 

Delmas et al. produced PVP-stabilized rhodium nanoparticles using the method reported by Hirai [32] to perform catalytic hydrogenation of oct-l-ene in a two-liquid-phase system [40]. These authors investigated the effect of various parameters on nanoparticle stability and activity under more or less severe conditions. It was also shown that PVP/Rh colloids could be reused twice or more, without any loss of activity. 

Fig. 14 Summary of the best results obtained in the Ir-catalyzed hydrogenation using nanoparticles stabilized with furanoside diphosphite ligands 14 and 15...

Application of amphiphilic block copolymers for nanoparticle formation has been developed by several research groups. R. Schrock et al. prepared nanoparticles in segregated block copolymers in the sohd state [39] A. Eisenberg et al. used ionomer block copolymers and prepared semiconductor particles (PdS, CdS) [40] M. Moller et al. studied gold colloidals in thin films of block copolymers [41]. M. Antonietti et al. studied noble metal nanoparticle stabilized in block copolymer micelles for the purpose of catalysis [36]. Initial studies were focused on the use of poly(styrene)-folock-poly(4-vinylpyridine) (PS-b-P4VP) copolymers prepared by anionic polymerization and its application for noble metal colloid formation and stabilization in solvents such as toluene, THF or cyclohexane (Fig. 6.4) [42]. 

Figure 15.28 TEM images of (a) Au nanoparticle arrays in mesoporous silica film (b) superlattice of extracted Au nanoparticles stabilized with 1-dodecanethiol.

Siekmann B. and Westesen K., Melt-homogenized sohd hpid nanoparticles stabilized by the nonionic surfactant tyloxapol. II. Physicochemical characterization and lyo-philization, Pharm. Pharmacol. Lett., 3, 225, 1994. 

Xu J, Han X, Liu H L, Hu Y (2005) Synthesis of monodisperse gold nanoparticles stabilized by gemini surfactant in reverse micelles. J Dispers Sci Technol 26 473-476... 

Pt/Ru bimetallic nanoparticles were prepared by coreduction of the corresponding metal salts in the presence of glucose (26). EXAFS data indicated the existence of a Pt-Ru bond in this case, proving the formation of bimetallic nanoparticles. Pd/Rh bimetallic nanoparticles, stabilized by PVP, were also prepared by the alcohol reduction method (27). 

In the coreduction of the corresponding two metal salts by tetraoctylammonium triethylhydroborate in THF, Pt/Ru (37) and Pt/Rh (13,38) bimetallic nanoparticles, stabilized by tetraoctylammonium bromide, were obtained. No metal borate was found in the product. 

Torigoe and Esumi proposed silver(I) bis(oxalato)palladate(II) as a precursor of Ag/Pd bimetallic nanoparticles stabilized by PVP (45). Photoreduction of the aqueous precursor in a quartz vessel gave Ag/Pd bimetallic nanoparticles at various concentrations. The particles deviate from spherical ones but are uniform. Each particle contains both metal elements, as confirmed by EDX measurement. The size can be changed with concentration of the precursor. The average composition of... 

Scanning tunneling microscopy (STM) has been used to determine the dimensions of metal nanoparticles stabilized by alkylammonium salt in combination with high-resolution TEM (51). The difference between the diameter determined by STM (cl in Fig. 9.1.6) and that determined by TEM (clM in Fig. 9.1.6) allows estimation... 

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