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7/29/2019 L-17 Synthesis Nano Microemulsion
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Synthesis of Nanomaterials
by Microemulsion Technique
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Outline
Microemulsion technique
Influence factors on synthesis Application on synthesis of nanomaterials
Conclusions
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Microemulsion Technique
Definition of microemulsion
---coined by J. H. Schulman in 1959
Components: surfactant, water, organic phase;
Thermodynamics: stable, even when centrifuge;
Size of droplets: 10-100nm; Optical character: transparent/subtransparent, isotropy.
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Synthesis procedures
Microemulsion containing
reactant A
Microemulsion containing
reactant B
Collision and coalescenceof droplets
Chemical reaction occurs
Microemulsion Technique
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Synthesis procedures
Microemulsion containing
reactant A
Add reducing agent
(reactant B)
Chemical reaction occurs
Microemulsion Technique
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Influence Factors on Synthesis
Size of water droplets
J.Lin, et al. J. Am. Chem. Soc. 2002, 124, 11514-11518
D. Gao et al., J. Am. Chem. Soc. 2005, 127, 4574-4575
Fig1.Relationship between the average size
of the TiO2 nanoparticles and the Wo value
(water, AOT, cyclohexane,
titanium isopropoxide in 1-hexanol)
Fig2.Plot of the Au cluster size
in diameter as a function ofR.
(AOT, n-heptane, water, HF, KAuCl4)
water/surfactant (Wo; R) diameter of droplets Surfactants and organic solvents
Nature of precipitating agent
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Fig. 1. XRD patterns of silica-supported rhodium catalysts Rhodium
content, 2.0 wt.%; synthesis time for rhodiumhydrazine particle,
30 min.
Surfactants and organic solvents
T. Hanaoka, Applied Catalysis A: General, 190, 2000, 291296
Influence Factors on Synthesis
7/29/2019 L-17 Synthesis Nano Microemulsion
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Influence Factors on Synthesis
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Nature of precipitating agent
Fig5.Effect of hydrazine concentration on the size of nickel nanoparticles.
[NiCl2] ) 0.05 M; water/CTAB/n-hexanol =22/33/45; 73.
Dong-Hwang Chen, Chem. Mater., Vol. 12, No. 5, 2000 1354
Influence Factors on Synthesis
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Table 1 Influence of several parameters on the Pd-based catalysts
Influence Factors on Synthesis
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Synthesis of Nanomaterials
Oxide nanomaterials
Inorganic compounds
Inorganic composites
Organic inorganic composites Polymer nanomaterials
Representative Examples Of Nanoparticulate Metals Prepared by Microemulsion
Metallic nanomaterials
7/29/2019 L-17 Synthesis Nano Microemulsion
12/20Ming-Li Wu, Langmuir, 2001, 17, 3877-3883
AOT/isooctane
Synthesis Pd, Au, Au/Pd nanoparticles
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J. Phys. Chem. B.;(Article); 2006; ASAP ArticleS. Iijima, et al.J. Phys. Chem. B. 2006. 110, 5849-5853
Supramolecular Catalysts for the Gas-phase
Synthesis of Single-walled Carbon Nanotubes(dimethyldioctylammonium bromide, toluene, MoCl3, FeCl3, water)
S h i f N i l
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Synthesis of Nanomaterials
Oxide nanomaterials
Survey from the Literature of Oxides Prepared from Microemulsions
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H. P. Wu. et al., Chem. Mater. 2006, 18, 1817-1820
Preparation of Monodisperse GeO2 Nanocubes in a
Reverse Micelle System
GeCl4, heptane (or octane), CTAB
Fig. (a) TEM image of a single GeO2 cube. (b) SAED pattern of the particle in a;
(c) illustration of the cubelike shape of the single crystal in a; (d) and (e) SEM images
at different magnifications. Scale bar in e is 500 nm.
S th i f N t i l
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Synthesis of Nanomaterials
Inorganic compounds
aqueous solutions : Ni(NO3) and Na2S, respectively
Khiew et al. Materials Letters, 58, 2004, 762767
0.010M
0.050M
0.100M
[Ni2+]/[S2-]:
Synthesis NiS nanoparticles by sugar-ester
S th i f N t i l
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Synthesis of Nanomaterials
Inorganic composites
polyoxyethylene (15) cetyl ether (C-15), cyclohexane and water.(tetraethylorthosilicate, TEOS)
Fig.TEM photographs of SiO2-coated Rh nanoparticles
prepared with hydrolysis times of (a) 1, (b) 5 and (c) 30 minutes.
T. Tago, Journal of Materials Science, 37, 2002, 977 982
Synthesis Rh/SiO2 nanoparticles
S th i f N t i l
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Organicinorganic compositesSynthesis of Nanomaterials
Synthesis Semiconductor Nanoparticle-Polymer Composites
Microemulsion (CVDAC) CdS, CdS-ZnS
in situ polymerization(AIBN)
nanoparticles incorporated into
the polymerized CVDAC
(a) SEM image, (b) FE-SEM image
Hirai et al. J. Phys. Chem. B, 2000, 104, 8962-8966
S th i f N t i l
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Polymer nanomaterials
Synthesis of Nanomaterials
Synthesis Poly (methyl methacrylate)
bysodium dodecyl sulfate (SDS)
Fig. Polarizing optical microscopy photograph of PMMA
Wan Jiang,et al. J. Polym. Sci., A, 2004, 42, 733-741
C l i
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Advantages of Microemulsion Technique
Metal particles are reduced directly in microemulsion andcan be used as a catalyst in suspension without furtherthermal treatment.
A narrow particle size distribution can be obtained.
The particle size can be controlled to a great extent. Bimetallic particles can be obtained at room temperature.
No effect of the support on the formation of the particles.
Conclusions
Disadvantages of Microemulsion Technique Amount of catalyst prepared from a single microemulsion.
Recovery and recycling of the liquid phase.