L-17 Synthesis Nano Microemulsion

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


reactant B

Collision and coalescenceof droplets

Chemical reaction occurs



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Synthesis procedures


reactant A

Add reducing agent

(reactant B)

Chemical reaction occurs



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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



8/20T. Hanaoka, Applied Catalysis A: General, 190, 2000, 291296



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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



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Table 1 Influence of several parameters on the Pd-based catalysts



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Oxide nanomaterials

Inorganic compounds

Inorganic composites

Organic inorganic composites Polymer nanomaterials

Representative Examples Of Nanoparticulate Metals Prepared by Microemulsion

Metallic nanomaterials


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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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.

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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

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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

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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

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Polymer 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.

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L-17 Synthesis Nano Microemulsion