Volume I: Synthesis


Content
1.1 INTRODUCTION...................................................................................................................... 1
1.2 FORMATION MECHANISMS OF MICELLES AND MICROEMULSIONS ........................................ 3
1.2.1 Simple Geometric Factors ............................................................................................ 3
1.2.2 The Critical Micelle Concentration (CMC) for Surfactants......................................... 5
1.2.3 Solubilization and Formation of Microemulsions ........................................................ 6
1.3 SYNTHESIS OF NANOPARTICLES FROM W/O MICROEMULSIONS (REVERSED MICELLES) ...... 9
1.3.1 Preparation of Nanoparticles of Metals ..................................................................... 10
1.3.2 Preparation of Nanoparticles of Metal Sulfides ......................................................... 11
1.3.3 Preparation of Nanoparticles of Metal Salts.............................................................. 12
1.3.4 Preparation of Nanoparticles of Metal Oxides........................................................... 12
1.3.5 Preparation of Nanoparticles of Other Compounds................................................... 13
1.3.6 Synthesis of Nanowires Using Reversed Micelles ...................................................... 13
1.3.7 Synthesis of Composite Nanoparticles Using Reversed Micelles ............................... 14
1.4 SYNTHESIS OF ORGANIC NANOPARTICLES FROM O/W MICROEMULSIONS .......................... 14
1.4.1 Introduction ................................................................................................................ 14
1.4.2 Synthesis of Styrene Latex Nanoparticles from O/W Microemulsions........................ 15
1.4.3 Synthesis of Methylmethacrylate Nanoparticles from O/W Microemulsions.............. 16
1.5 APPLICATIONS ..................................................................................................................... 16
1.6 PROSPECTS .......................................................................................................................... 17
References ........................................................................................................................... 17
2.1 INTRODUCTION.................................................................................................................... 23
2.2 METAL NANOPARTICLES ..................................................................................................... 25
2.2.1 Background ................................................................................................................ 25
2.2.2 Precious Metal Nanoparticles .................................................................................... 26
2.2.3 Transition Metal Nanoparticles.................................................................................. 27
2.3 OXIDE NANOPARTICLES ...................................................................................................... 30
2.3.1 General Background of Nano-Oxides ........................................................................ 30

2.3.2 Ceramic Oxide Nanoparticles .................................................................................... 31
2.3.3 Specific Ceramic—SiC ............................................................................................... 33
2.3.4 Functional Oxide Nanoparticles................................................................................. 33
2.4 COMPOUND SEMICONDUCTOR NANOPARTICLES ................................................................. 35
2.4.1 Background ................................................................................................................ 35
2.4.2 III-V Semiconductor Nanoparticles............................................................................ 35
2.4.3 II-VI Semiconductor Nanoparticles............................................................................ 36
2.4.4 Other Typical Semiconductor Nanoparticles ............................................................. 38
2.4.5 Conclusions ................................................................................................................ 38
2.5 SUPERCONDUCTOR NANOMATERIALS ................................................................................. 39
2.5.1 Background ................................................................................................................ 39
2.5.2 YBCO Cuprates .......................................................................................................... 39
2.5.3 Bi-Series Cuprates...................................................................................................... 40
2.5.4 Tl-Series Cuprates ...................................................................................................... 40
2.6 ELEMENT NANOSTRUCTURES .............................................................................................. 40
2.6.1 Background ................................................................................................................ 40
2.6.2 Carbon Nanosystems .................................................................................................. 41
2.6.3 IV Semiconductor Nanoclusters ................................................................................. 42
2.7 INTRAZEOLITE TOPOTAXY IN MESOPOROUS MATERIALS .................................................... 43
2

www.pdfgrip.com


2.8 CONCLUSIONS ..................................................................................................................... 44
References ........................................................................................................................... 44
3.1 INTRODUCTION.................................................................................................................... 47
3.2 FORCED HYDROLYSIS AND CONTROLLED RELEASE OF ANIONS .......................................... 48
3.2.1 Forced Hydrolysis ...................................................................................................... 48
3.2.2 Precipitation by Controlled Release of Anions........................................................... 49

3.2.3 Nucleation and Growth .............................................................................................. 51
3.2.4 Factors Controlling Particle Sizes ............................................................................. 55
3.3 CHEMICAL CO-PRECIPITATION............................................................................................ 59
References ........................................................................................................................... 62
4.1 INTRODUCTION.................................................................................................................... 63
4.2 PRINCIPLES OF THE SYNTHESIS TECHNIQUE ........................................................................ 64
4.3 EXPERIMENTAL APPROACH ................................................................................................. 65
4.3.1 Silica Sol-Gel Processing ........................................................................................... 65
4.3.2 Metal Alkoxide Method............................................................................................... 70
4.3.3 Pechini Processing ..................................................................................................... 75
4.3.4 Sol-gel Thin Film Processing ..................................................................................... 78
4.4 EXAMPLES OF THE SYNTHESIS PROCESS ............................................................................. 79
4.4.1 Organic/Inorganic Hybrid Network Materials Based on Silica sol-gel Approach—
PTMO TMOS nanocomposites (Huang, et al., 1987).......................................................... 80
4.4.2 Composited Oxide Powders—MgAl2O4 spinel from a heterometallic alkoxide
(Varnier, et al., 1994) .......................................................................................................... 82
4.4.3 Nanocrystalline Thin Films of Composited Oxides—Co and RE(rare earth)-doped Co
ferrite nanocrystalline films (Cheng, et al., 1998; Yan, et al., 1998; Cheng, et al., 1999).. 83
4.4.4 Glass/Non-Oxide Nanocomposites by sol-gel Technique—LaF3 microcrystals in solgel silica .............................................................................................................................. 86
4.5 CURRENT STATUS OF THE TECHNIQUE, LIMITATIONS AND PROSPECTS ............................... 87
References ........................................................................................................................... 87
5.1 INTRODUCTION.................................................................................................................... 91
5.2 PRINCIPLES OF CHEMICAL VAPOR DEPOSITION ................................................................... 92
5.3 EXPERIMENTAL APPROACH ................................................................................................. 95
5.3.1 Chemical Vapor Deposition (CVD)............................................................................ 96
5.3.2 Chemical Vapor Condensation (CVC) ....................................................................... 96
5.3.3 Particle–Precipitation–Aided Chemical Vapor Deposition ....................................... 97
5.3.4 Catalytic Chemical Vapor Deposition........................................................................ 99
5.4 EXAMPLES OF NANOSTRUCTURED MATERIALS ................................................................. 100
5.4.1 Semiconductor Quantum Dots.................................................................................. 100

5.4.2 Ceramic Nanostructured Materials.......................................................................... 104
5.4.3 Carbon Nanotubes.................................................................................................... 112
5.4.4 Diamond ................................................................................................................... 121
5.5 SUMMARY ......................................................................................................................... 126
References ......................................................................................................................... 127
6.1 INTRODUCTION.................................................................................................................. 131
6.2 PRINCIPALS OF AEROSOL SYNTHESIS/THEORY.................................................................. 134
6.2.1 Early Work ............................................................................................................... 135
6.2.2 Homogeneous Nucleation......................................................................................... 137
6.2.3 Collision-Coalescence Growth................................................................................. 141
6.2.4 Forced Flow Production .......................................................................................... 153
6.3 EXPERIMENTAL ................................................................................................................. 159
6.3.1 Inert Gas Condensation Methods ............................................................................. 160
6.3.2 Arc (Spark) Evaporation Sources............................................................................. 166
6.3.3 Gas-Phase Reaction in a Free Jet ............................................................................ 170
3

www.pdfgrip.com


6.3.4 Laser Ablation and Laser Driven Chemical Reaction Sources ................................ 172
6.3.5 Sputtering ................................................................................................................. 175
6.4 CONCLUSIONS ................................................................................................................... 176
References ......................................................................................................................... 177
7.1 INTRODUCTION.................................................................................................................. 180
7.2 SPUTTERING ...................................................................................................................... 181
7.2.1 Principle of Sputtering.............................................................................................. 181
7.2.2 Sputtering Systems.................................................................................................... 181
7.2.3 Examples of Multilayer Structures Prepared by Sputtering ..................................... 184
7.2.4 Current Status of Sputtering ..................................................................................... 188

7.3 PULSED LASER DEPOSITION .............................................................................................. 189
7.3.1 Principle of Pulsed Laser Deposition....................................................................... 189
7.3.2 Deposition of Nano-Scale Metal Oxide Thin Films.................................................. 190
7.3.3 Examples of Multilayer Structures Prepared by Pulsed Laser Deposition .............. 194
7.3.4 Current Status of Pulsed Laser Deposition .............................................................. 197
References ......................................................................................................................... 197
8.1 INTRODUCTION.................................................................................................................. 199
8.2 PRINCIPLES OF LASER ABLATION ...................................................................................... 204
8.2.1 Fundamental Process ............................................................................................... 204
8.2.2 Theoretical Model .................................................................................................... 205
8.3 PROCESSING EXPERIMENTS ............................................................................................... 210
8.3.1 Process Chamber...................................................................................................... 210
8.3.2 Processing Procedures ............................................................................................. 212
8.3.3 Laser Absorption Spectroscopy ................................................................................ 213
8.3.4 Process Variables..................................................................................................... 218
8.4 MICROSTRUCTURE ............................................................................................................ 221
8.4.1 NbAl3 Nanocrystalline Powders ............................................................................... 221
8.4.2 NbAl3/Al Multilayer Thin Film ................................................................................. 224
8.5 CONCLUSIONS ................................................................................................................... 226
References ......................................................................................................................... 226
9.1 INTRODUCTION.................................................................................................................. 229
9.2 PHYSICAL VAPOR DEPOSITION: EVAPORATION AND SPUTTERING .................................... 229
9.2.1 Deposition: Film Nucleation and Growth ................................................................ 229
9.2.2 Evaporation .............................................................................................................. 231
9.2.3 Sputtering ................................................................................................................. 232
9.2.4 Examples .................................................................................................................. 233
9.3 THERMAL SPRAYING ......................................................................................................... 242
9.4 ELECTRODEPOSITION AND ELECTROLESS DEPOSITION ...................................................... 245
9.5 SUMMARY ......................................................................................................................... 252
References ......................................................................................................................... 252

10.1 INTRODUCTION................................................................................................................ 258
10.2 NANOLITHOGRAPHY TECHNIQUES .................................................................................. 259
10.2.1 Electron Beam Lithography (EBL)......................................................................... 259
10.2.2 X-ray Lithography (XRL)........................................................................................ 266
10.2.3 Extreme Ultraviolet Lithography (EUVL) .............................................................. 271
10.3 EXAMPLES OF THE ARTIFICIAL PATTERNED NANOSTRUCTURES ..................................... 273
10.4 SUMMARY AND PROSPECTS ............................................................................................. 277
References ......................................................................................................................... 278
11.1 INTRODUCTION................................................................................................................ 280
11.2 ION IMPLANTATION FACILITY ......................................................................................... 281
11.3 ION-SOLID INTERACTIONS ............................................................................................... 283
11.3.1 Ion Stopping Mechanisms....................................................................................... 283
4

www.pdfgrip.com


11.3.2 Nuclear Stopping .................................................................................................... 285
11.3.3 Electronic Stopping ................................................................................................ 293
11.3.4 Ion Ranges.............................................................................................................. 295
11.3.5 Channeling ............................................................................................................. 297
11.3.6 Sputtering ............................................................................................................... 299
11.3.7 Radiation Damage.................................................................................................. 300
11.4 ALLOYING, AMORPHIZATION AND PHASE TRANSFORMATION......................................... 304
11.5 NANOCRYSTALLINE PHASES CREATED BY ION IMPLANTATION ...................................... 307
11.5.1 Ion Implantation and Nucleation............................................................................ 312
11.5.2 Influence of the Matrix Structure on the Nanocrystal Structure and Orientation .. 313
11.5.3 Nanocrystal Size Control........................................................................................ 316
11.6 ION BEAM MIXING AND SPUTTER DEPOSITION ............................................................... 319
References ......................................................................................................................... 320

APPENDIX ............................................................................................................................... 325

5

www.pdfgrip.com


1.1 Introduction
Nanoparticles play a vital role in high performance materials in high technology
industries. The studies of nanoparticles started in the early 1980's and have now become
one of the hottest worldwide research fields (Pui and Chen, 1997).
There are four main processing approaches for the preparation of nanoparticles by
chemical method (Riman, 1993): (1) chemistry in liquid phase including direct strike
(Murata, et al., 1976), nonsolvent addition (Mulder, 1970), solvent removal (Cheng, et
al., 1986), gel drying (sol-gel) (Perthuis, And Colomban, 1984) and precipitation from
homogeneous solution (Gordon, et al., 1959); (2) chemistry between heterogeneous
phase including hydrothermal synthesis (Adair, et al., 1987), molten salt synthesis
(Arendt, et al., 1979), pyrolysis (Wada, et al., 1987) and spark erosion (Berkowitz, et al.,
1987); (3) chemistry in a droplet including emulsions (Woodhead, et al., 1980), micelles
(Gobe, et al., 1983) or microemulsions (Kandori, et al., 1988) and aerosols (Balboa, et
al., 1987); (4) chemistry in the vapor phase including heating method (Mazdiyasni, et al.,
1965), vapor precursors (Iwama, et al., 1982), liquid precursors (Kagawa, et al., 1983)
and solid precursors (Watanabe, et al., 1986). The most attractive methods are those
which synthesize in the liquid medium, including methods of precipitation, reduction,
dehydration, solvent evaporation, reversed micelle technology and microemulsion
polymerization, etc. In this chapter, we will focus on the nanoparticles made from both
W/O microemulsion (reversed micelles) and O/W microemulsion procedures.
Hence it is necessary to introduce the definition of micelles and microemulsions before
dealing with the principles and practices of forming nanoparticles from micelles and
microemulsions. Micelles are aggregates of surfactants in a liquid medium which are

formed when the surfactant concentration exceeds the critical micelle concentration
(CMC) (McBain and Salmon, 1920). It must be mentioned that this definition is only for
normal micelles; for the case of reversed micelles it is not necessary to have a CMC. In
the normal micelle the surfactant is orientated in such a way that the hydrophobic
hydrocarbon chains are towards the interior of the micelle, leaving the hydrophilic
groups in contact with the aqueous medium. Above the CMC, the physical state of the
surfactant molecules dissolved in water changes dramatically, and additional surfactant
exists as aggregates or micelles. Thus, the bulk properties of the surfactant, such as
osmotic pressure, turbidity, solubilization, surface tension, conductivity and selfdiffusion, change around the critical micelle concentration (Fig. 1.1).
Figure 1.1 Changes in concentration dependence of a wide range of physicochemical quantities around the critical micelle concentration (After Lindman,
1980).

1

www.pdfgrip.com


If the micelles are formed in non-aqueous medium, the aggregates are called reversed
micelles, as in this case the hydrophilic head groups are now towards the core of the
micelle while leaving the hydrophobic groups outside of the micelles. The driving force
for formation of reversed micells is the dipole-dipole interactions of the surfactant. The
number of aggregates is usually small and not sensitive to the surfactant concentration
and thus there is no obvious CMC (Zhao, 1991; Gutmann and Kertes, 1973; Kertes and
Gutmann, 1976). In both cases (micelles and reversed micelles), only a small amount of
solubilized hydrophobic (usually oil) or hydrophilic (usually water) material exists in the
micelles (Fig. 1.2). However, the solubilization can be enhanced if the concentration of
surfactant is increased further. As the inside pool of water or oil is enlarged or swollen,
the droplet size increases up to a dimension much larger than the monolayer thickness of
the surfactants. In this case, we call them microemulsions or swollen micelles. What we
now describe as the preparation of nanoparticles from the reversed micelles may be

better described as preparation from swollen reversed micelles or water-in-oil
microemulsions.
Figure 1.2 The structure of micelles and microemulsions (O/W and W/O) (After
Overbeek et al., 1983).

As the surfactant concentration increases further, micelles can be deformed and can
change their shapes to rodlike micelles, hexagonal micelles and lamellar micelles or
2

www.pdfgrip.com


liquid crystals (Fig. 1.3). It is these changes that make it possible to prepare different
shapes of nanoparticles from micelle synthesis microreactors.

1.2 Formation Mechanisms of Micelles and Microemulsions
1.2.1 Simple Geometric Factors
The structures of micelles can be simply determined by the geometric factors of the
surfactant at the interface, including head group area a0, the alkyl chain volume v and the
maximum length lc (to which the alkyl chain can extend). According to Israelachvili
(Israelachvili, et al., 1976), the packing considerations govern the geometry of
aggregation into micelles, vesicles and liposomes.
Figure 1.3 A schematic phase diagram of surfactant-oil-water systems showing
a variety of self-assembled structures (After Liu, J., et al., 1996).

These obey the following rules:
1.
2.
3.
4.

Spherical micelles require v/a0lc < 1/3,
Non-spherical micelles require 1/3 < v/a0lc < 1/2,
Vesicles or bilayers require 1/2 < v/a0lc < 1, and
Inverted micelles require 1 < v/a0lc.

In each case, the limits for the packing parameter v/a0lc can be evaluated from simple
geometry (Fig. 1.4) (Israelachvili, 1985). However, the change of environment will
affect these parameters, and thus dictate the molecular packing at the interface.

3

www.pdfgrip.com


Figure 1.4 The relationship between aggregate type and geometry on the
packing requirements of surfactant head group and chains (Israelachvili, 1985).

4

www.pdfgrip.com


1.2.1.1 Spherical Micelles
Spherical micelles are usually formed by anionic surfactants with or without cosurfactants. For an O/W micelle, this can be done by adjusting the repulsion (double
layers) between adjacent head groups, resulting in large values for a0. In this case, the
micelle radius is approximately equal to the maximum stretched out length of the
surfactant molecule and therefore the aggregates are very small. Bellare et al. (1988),
using small-angle neutron scattering (SANS), have successfully visualized a spherical
micelle of radius (3.0 ± 0.3) nm for a cryo-TEM image of a 10 mmol • dm-3 solution of

ditetradecyl-dimethyl-ammonium acetate.
1.2.1.2 Cylindrical Micelles
It is a quite common phenomenon that micelles grow as the preferred surface curvature
decreases. Any change that reduces the effective head group area will lead to the growth
of micelles. There are basically three ways to form cylindrical micelles: (1) addition of a
co-surfactant with a very compact head group, i.e. n-alkanol for which the–OH group is
small in comparison with a charged sulfate group, (2) changing the counterion, i.e.,
changing Na+ to Mg2+ will significantly reduce the electric double layer thickness, and
hence reduce the effective volume (size) of the head groups, (3) changing the
hydrophilicity of non-ionic head groups by electrolyte addition or temperature change;
i.e., for micelles formed by surfactants with poly(oxyethylene)(PEO) head groups, the
head groups are sensitive to changes of solvency (Tadros, 1987).
1.2.2 The Critical Micelle Concentration (CMC) for Surfactants
The CMC of a surfactant system depends on the minimum value of the interaction free
energy per molecule µN0. The minimum arises from the hydrophilicity of the head group,
tending to increase the area per molecule, while the hydrophobicity of the alkyl tail
tends to cause a decrease due to the hydrophobic bonding. From this concept, one is able
to predict how various structural features of surfactant molecules will affect their CMC
values.
Table 1.1 Typical CMC values for ionic surfactants at 25 °C
Surfactant

CMC/mmol • dm-3

C12H25SO4Na

8.1

C12H25SO4Li

8.9

C12H25SO3Na

10

C12H25CO3K

12.5

C12H25NH3Cl

14.7

5

www.pdfgrip.com


C12H25NC2H5Cl

15
16

C12H25N(CH3)3Br
C12H25N(CH3)3Cl

17

For these ionic surfactants, there is little difference between anionic and cationic head

groups, since both have comparatively high CMC values, provided that the counterion is
monovalent. Usually, the CMC values for these systems are 1–20 mmol • dm-3 (Table
1.1). However, to change the counterion to a multivalent one tends to decrease the CMC
considerably.
For non-ionic surfactants, such as CxEy type, where x is the carbon number in the range
of 8–18, and y is the ethylene oxide group in the range of 3–20, the CMC value is
extremely low, i.e., 0.04–3 mmol • dm-3, depending on the structure of the molecules
(Table 1.2).
Table 1.2 Typical CMC values for non-ionic surfactants at
25 °C
Surfactant

CMC/mmol · dm-3

C12H25(OCH2CH2)4OH

0.046

C12H25(OCH2CH2)6OH

0.087

C12H25(OCH2CH2)8OH

0.109

C12H25(CH3)NO

2.1

1.2.3 Solubilization and Formation of Microemulsions
1.2.3.1 Solubilization
The term solubilization in this chapter refers to the dissolution of hydrophobic
(hydrophilic) materials into water (or oil) to an extent greatly exceeding their normal
solubilities in water (oil). The interior of a micelle provides a hydrophobic (hydrophilic)
environment in which non-polar (or polar) compounds can be accommodated. As a
result, the solubility of hydrophobic (or hydrophilic) material increases dramatically
with increasing surfactant concentration when it reaches the CMC as shown in Fig. 1.1.
The solubility behavior of surfactants is anomalous as the temperature is increased to a
value at which there is a sudden increase in solubility and the material then becomes
very highly soluble (Krafft, 1899). This is illustrated in Fig. 1.5.
6

www.pdfgrip.com


Figure 1.5 Schematic representation of solubility versus temperature showing
location of the Krafft point (After Shinoda, 1974).

The process of solubilization has many applications in industrial preparations, for
example, in solubilization of insoluble drugs for intravenous injection. The process of
solubilization by micellar systems is also important in detergency, whereby fats and oils
are removed by incorporation into the hydrocarbon core of the micelle. There are four
general possible ways for the incorporation of the solubilization: (1) in the hydrocarbon
core of the micelle; (2) orientation in the micelle which could be deep or shallow; (3) in
the hydrophilic portion of the surfactant (e.g., ethylene oxide of non-ionic surfactants);
and (4) adsorption on the surface of the micelle (Fig. 1.6).
Figure 1.6 Schematic representation of four ways of solubilization of micelles.

7

www.pdfgrip.com


1.2.3.2 Microemulsions
The microemulsion systems were first reported by Hoar and Schulman (1943), who
described transparent or translucent systems, formed spontaneously when oil and water
were mixed with a relatively large amount of an ionic surfactant combined with a
cosurfactant, e.g., a medium size alcohol. Later, in 1959, Schulman and co-workers
(Schulman, et al., 1959) introduced the concept of microemulsions as transparent or
translucent systems with a spherical or cylindrical size range of 8–100 nm. This is the
right size for preparing spherical and rod-like nanometer particles.
The solubilization theories of microemulsions have been proposed by Shinoda (Shinoda,
1974), who considered microemulsions as solubilized systems extended from the threecomponent phase diagrams of water-surfactant and co-surfactant (Fig. 1.7). It is clear
that in the phase diagrams there are two isotropic regions: one in the top corner, the so
called L2 phase or inverse micelles, and one in the left corner, i.e., L1 phase or normal
micelles. The L2 phase is capable of dissolving a large amount of water, thereby forming
a W/O microemulsion. Similarly, the L1 phase can solubilize oil to form an O/W
microemulsion. Thus, O/W microemulsions can be considered as an extension of the L2
phase, whereas W/O microemulsions can be considered as an extension of the L1 phase.
Figure 1.7 Schematic representation of a tree-component phase diagram for
water-surfactant and cosurfactant (After Overbeek et al., 1983).

The advantages of microemulsions in many industrial processes are distinct: from their
spontaneous formation, thermodynamic stability to lack of aging. Applications are based
on the low interfacial tension (as in tertiary oil recovery), the possibility of preparing
both hydrophilic and hydrophobic nearly homogeneous nanoparticles, the small droplet
size produced and their isodisperse nature.

8

www.pdfgrip.com


1.3 Synthesis of Nanoparticles from W/O Microemulsions (Reversed Micelles)
O/W microemulsions (reversed micelles) can be formed by ionic surfactants with double
long alkyl chains alone, such as, AOT (Aerosol OT) by or a mixture of ionic and
nonionic surfactants with a short oxyethylene chain dissolved in organic solvents.
Reversed micelles are usually thermodynamically stable mixtures of four components:
surfactant, co-surfactant, organic solvent and water. AOT, SDS (sodium dodecyl sulfate),
CTAB (cetyltrimethy lammonium bromide) and Triton-X are the usual surfactants. Cosurfactants are often aliphatic alcohols with a chain length of C6–C8. Organic solvents
used for reversed micelle formation are usually alkane or cycloalkane with 6 to 8
carbons.
Reversed micelles can solubilize relatively large amounts of water. It is this water pool
that makes the reversed micelles particularly favorable for the synthesis of nanoparticles
because the water pool is in the range of nanometer size which can be controlled by
adjusting the water content. Solubilization of water in the reverse micelles can be
expressed by w, the ratio of water to surfactant concentrations (w = [H2O]/[surfactant]).
w is an important parameter in determining the size of the reversed micelles and the
structure of water. For a typical spherical AOT reversed micelle, there is a linear
relationship between the diameter of the water pool (D) and w. D = 0.3 w when w is
larger than 15 (Pileni, et al., 1985). In addition, w is related to the structure of water. For
an AOT reverse micelle, when w increases, the structure of the water changes from
bound water to free water.
Due to the controllable water pool, reversed micelles are particularly favorable for the
preparation of monodisperse nanoparticles with various particle sizes. The nanoparticles
can be fabricated using the reversed micelles having the following two features: (1) the
nanoparticles are harder to aggregate because the surface of the nanoparticles is covered
with surfactants; (2) the surface of the particles can be modified further.
Preparation of nanoparticles using reverse micelles can be dated back to the pioneer

work of Boutonnet et al. (Boutonnet, et al., 1982). In 1982 they first synthesized
monodispersed Pt, Rh, Pd, Ir nanoparticles with diameters of 3–6 nm. After that, many
nanoparticles were synthesized and the method of preparing nanoparticles using reverse
micelles became a world wide interest in nanoscience and nanotechnology. In the
following sections we will review the synthesis of various nanoparticles using the
technique of reversed micelles.
The general method to synthesizing nanoparticles using reverse micelles is
schematically illustrated in Fig. 1.8. This can be divided into three cases. The first one is
the mixing of two reverse micelles. Due to the coalescence of the reverse micelles,
exchange of the materials in the water droplets occurs, which causes a reaction between
the cores. Since the diameter of the water droplet is constant, nuclei in the different
water cores can not exchange with each other. As a result, nanoparticles are formed in
the reversed micelles. The second case is that one reactant (A) is solubilized in the
reversed micelles while another reactant (B) is dissolved in water. After mixing the two
9

www.pdfgrip.com


reverse micelles containing different reactants (A and B), the reaction can take place by
coalescence or aqueous phase exchange between the two reverse micelles.
Figure 1.8 Schematic illustration of various stages in the growth of
nanoparticles in microemulsions (After Leung, at al., 1988).

There are essentially three procedures to form nanoparticles by reversed micelles:
precipitation, reduction and hydrolysis. Precipitation is usually applied in the synthesis
of metal sulfate (Qi, et al., 1996), metal oxide (Ayyub, et al., 1990; 1988), metal
carbonate (Kandori, et al., 1988; Pillai, et al., 1993) and silver halide (Dvolaitzky, et al.,
1983; Hou and Shah, 1988; Chew, et al., 1990) nanoparticles. In this method two reverse
micelles containing the anionic and cationic surfactants are mixed. Because every

reaction takes place in a nanometer-sized water pool, water-insoluble nanoparticles are
formed.
The reduction procedure is one of the most common ways to prepare metal nanoparticles
using W/O microemulsions. By dissolving the metal salts in the reversed micelles, the
salts undergo a dissociation step inside the aqueous domain. Following a reduction step
(Men+ → Me0), a subsequent precipitation of particles can take place inside the water
pools. Strong reduction agents such as N2H4, NaBH4 and sometimes hydrogen gas can
be used.
The hydrolysis procedure is usually used in the preparation of metal oxide nanoparticles.
It utilizes the hydrolysis properties of metal alkoxide dissolved in oil and reacting with
water inside the droplets.
1.3.1 Preparation of Nanoparticles of Metals
Since metals display surface catalytic properties, the synthesis of size-controllable and
monodisperse metal nanoparticles is of considerable importance. The reduction method
is one of the most common ways to prepare metal nanoparticles through reverse micelles.
10

www.pdfgrip.com


Boutonnet et al. have prepared platinum, palladium, rhodium and iridium nanoparticles
using reverse micelles (Boutonnet, et al., 1982; 1989). H2PtCl6 was dissolved in
CTAB/water/octanol reverse micelle. Subsequent reduction with hydrazine produced
nanoparticles. Pd particles were formed by reducing Pd(NH2)4Cl2 or K2PdCl4 with N2H4.
Rhodium particles were formed by reducing RhCl2 with bubbling hydrogen, whereas
iridium particles could be obtained by bubbling active hydrogen through 2% Pt-Al2O3 at
70°C. Ag and Au colloidial nanoparticles were successfully prepared by reducing the
AgNO3 and HAuCl4 in water/cyclohexane/PEGDE or PEGDE/water/n-hexane reverse
micelles (Barnickel and Wokaun, 1990), where NaBH4 was used as the reduction
reagent. Silver and copper salts of Aerosol OT can be used for the preparation of Ag and

Cu nanoparticles (Lisiecki and Pileni, 1993; Pileni, et al., 1993a; 1993b; Petit, et al.,
1993; Lisiecki and Pileni, 1995). Copper nanosized particles have been synthesized in
the reverse micelles using hydrazine as a reducing reagent. The size of Cu nanoparticles
can be controlled by the water content in the reversed micelles (Lisiecki and Pileni,
1995). Gold and silver nanoparticles were also produced by reducing gold chloride
tetrahydrate HAuCl4 with citric acid at 80°C for half an hour (Chen, et al., 1996; Frens,
1973; Enustun and Turkevich, 1963). Nanoparticles of other metals such as Co (Chen, et
al., 1994; Eastoe, et al., 1996), Ni (Lopez-Quintela and Rivas, 1993) and metal alloys
FeNi (Lopez-Quintela and Rivas, 1993), Cu3Au (Sangregorio, et al., 1996) and Co-Ni
(Nagy, 1989) have also been synthesized using the reversed micelles.
1.3.2 Preparation of Nanoparticles of Metal Sulfides
Colloidal semiconductors are attracting much interest due to their applications as
enhancement of photoreactivity and photocatalysis and non-linear optical properties.
The key to synthetic investigation of this kind of nanoparticles must be the careful
control of semiconductor size and size distribution. The precipitation method is usually
applied in the preparation of metal sulfide particles (Motte, et al., 1992; Hirai, et al.,
1994; Ward, et al., 1993; Boalkye, et al., 1994; Modes and Lianos, 1989). CdS particles
have been synthesized in AOT and Triton reversed micelles with functional surfactant
such as cadmium lauryl sulfate and cadmium AOT (Petit, et al., 1990; Petit and Pileni,
1988). The average diameters of the particles were found to depend on the relative
amount of Cd2+ and S2-. The particles obtained from AOT were smaller and more
monodisperse than those from the Triton reverse micelle. Colloidal CdS was prepared in
the mixed sodium AOT/cadmium AOT/isooctane reverse micelle (Motte, et al., 1992).
PbS nanoparticles can be prepared by mixing one polyoxyethylene dodecyl ether-nhexane reverse micelle, which supplies Pb2+ from electrolytes such as Pb(NO3)2 or
Pb(ClO4)2, and another reverse micelle that contains S2- from Na2S or H2S (Ward, et al.,
1993). A number of nanoparticle semiconductors such as CdS (Lianos and Thomas,
1987; Petit, et al., 1990; Pileni, et al., 1992; Karayigitoglu, et al., 1994), PbS (Ward, et
al., 1993; Eastoe, et al., 1996), CuS (Lianos and Thomas, 1987), Cu2S (Haram, et al.,
1996), Ag2S (Motte, et al., 1996), MoS3 (Boalkye, et al., 1994), CdSe (Steigerwald, et al.,
1988) have also been synthesized using this method.

In recent years apart from the synthesis of nanoparticles, surface modification of the
metal sulfide particles has attracted much interest. The modification of the
semiconductor surface is also very important either from the point of view of enhancing
11

www.pdfgrip.com


the stability of the nanoparticles or for providing unique physical and chemical
properties. An additional profit from this treatment is that it allows the particles to be
separated from the micellar solution and redispersed in another solvent. Some surfacecapped semiconductor nanoparticles have been synthesized with the cap agents such as
sodium hexamephosphlate (Meyer, et al., 1984; Petit and Pileni, 1988) of the surfacecapping agents such as thiophenol and phenyl (trimethyl) selenium (Steigerwald, et al.,
1988; Herron, et al., 1990; Dance, et al., 1984).
1.3.3 Preparation of Nanoparticles of Metal Salts
Many metal salts such as silver halide, metal sulfate and metal carbonate possess unique
properties. Precipitation methods are usually used to prepare the nanoparticles of these
materials. Silver halide nanoparticles were synthesized by reacting AgNO3 with sodium
halides in Aerosol OT W/O microemulsions (Dvolaitzky, et al., 1983; Hou and Shah,
1988; Chew, et al., 1990).
However, metal carbonate nanoparticles such as BaCO3, CaCO3 and SrCO3 were
prepared by bubbling CO2 through the reversed micelle solutions containing the
corresponding aqueous metal hydroxides. Kandori et al. (1987) used the hexaethylene
glycol dodecyl ether (HEGDE)/water/cyclohexane and calcium AOT based reverse
micellar system to synthesize CaCO3 nanoparticles with diameters of 5.4 nm. The
nanoparticle diameter from the CaAOT system was 48–130 nm (Kandori, et al., 1987;
1988). Nanoparticles of metal sulfate can also be synthesized by the precipitation
method. Nanoparticles of AgCl (Bagwe and Khilar, 1997) and AgBr (Chew, et al., 1990;
Monnoyer, et al., 1996) have been synthesized using reverse micelles.
1.3.4 Preparation of Nanoparticles of Metal Oxides
Nanoparticles of metal oxides are usually produced by the hydrolysis method in which

the metal alkoxides react with water droplets in the reverse micelles. Nanoparticles of
metal oxides such as ZrO2 (Kawai, et al., 1996), TiO2 (Chang, et al., 1994; Joselevich
and Willner, 1994; Chhabra, et al., 1995), SiO2 (Osseo-Asare and Arriagada, 1990;
Wang, et al., 1993; Arriagada and Osseo-Asare, 1995; Gan, et al., 1996; Chang and
Fogler, 1997; Esquena, et al., 1997), GeO2 (Kon-no, 1996), g-Fe2O3 (Lopez-Perez, et al.,
1997) and F2O3 (Liz, et al., 1994) have been synthesized. GeO2 nanoparticles can
directly be obtained from AOT-cyclohexane W/O microemulsions by adding anhydrous
cyclohexane solutions of Ge(OC2H4)4 into the microemulsions. And SiO2 nanoparticles
could be formed by adding Si(OC2H4)4 to the solubilized ammonia aqueous solution in
AOT and polyoxyethylated nonylphenyl ether W/O microemulsions. Similarly, ZrO2
nanoparticles can be obtained by hydrolyzing Zr(OC4H9)4 with sulfuric acid in
polyoxyethylene nonylphenyl ether-cyclohexane systems and then washed with
ammonia aqueous solution. TiO2 nanoparticles can be prepared by adding benzene
solution of TiCl4 to cetylbenzyldimethylammonium chloride-benzene W/O
microemulsions.

12

www.pdfgrip.com


1.3.5 Preparation of Nanoparticles of Other Compounds
YBa3CuO7-x particles were synthesized by co-precipitation of the oxalate salts of Y, Ba
and Cu nitrates in CTAB/n-butanol/n-octane reversed micelles (Ayyub, et al., 1988;
1990). BaFe12O19 particles were synthesized by the calcination of barium-iron carbonate
particles made by mixing the two reverse micelles containing the (NH4)2CO3 and a
mixture of aqueous Ba(NO3)2 and Fe(NO3)3 (Pillai, V., et al., 1993).
1.3.6 Synthesis of Nanowires Using Reversed Micelles
The nanoparticles fabricated in the reversed micelles are spherical particles in most
cases. However, since the optical, electric, and other properties of nanoparticles are

affected by the shape of nanoparticles, various shapes have been synthesized. For
example, cubic Pt nanoparticles have been synthesized and they showed extremely good
catalysis selectivity and activity (Ahmadi, et al., 1996a; 1996b). Addition of CdS
nanowire into the porous aluminum oxide film will be of potential use in photoelectronics (Routkevitch, et al., 1996). Qi et al., using reversed micelles of TX100/hexanol.cyclohexane/water, have successfully synthesized cubic BaSO4
nanoparticles (Qi, et al., 1997). They have found that the water content in the reversed
micelles greatly affected the shape of the nanoparticles. Cubic nanoparticles of BaSO4
were obtained in the higher content of water. On the other hand, in the non-ionic reverse
micelle C12E4/cyclohexane, adding 0.1 M BaCl2 and Na2CO3 aqueous solution to 0.2 M
C12E4/cyclohexane solution, and mixing the two reversed micelles, BaCO3 nanowires
were obtained (Fig. 1.9). Hopwood and Mann have also synthesized BaSO4 nanowire
using reversed micelles (Hopwood and Mann, 1997).
Figure 1.9 TEM micrographs and electron diffraction pattern of BaCO3
anowires synthesized in reversed micells (Qi, et al., 1997).

13

www.pdfgrip.com


1.3.7 Synthesis of Composite Nanoparticles Using Reversed Micelles
Composite nanoparticles are composed of two kinds of nanoparticles, not only modifing
the properties of single semiconductor nanoparticles, but also producing some new
electric and optical properties. The composite semiconductor nanoparticles can be
divided into sandwich type and shell-core type. Sandwich type CdS-TiO2 (Spanhel, et al.,
1987; Gopidas, et al., 1990; Lawless, et al., 1995 and CdS-SnO2 (Nasr, et al., 1997) have
been prepared and show prospects in solar cell application. On the other hand, shell-core
type composite nanoparticles such as CdS-ZnS (Hirai, et al., 1994), CdS/PbS (Zhou, et
al., 1993; 1994), CdS/HgS (Hasselbarth, et al., 1993; Mews, et al., 1994; Schooss, et al.,
1994; Kamalov, et al., 1996; Mews, et al., 1996), CdS/Ag2S (Han, et al., 1998),
CdS/CdSe (Tian, et al., 1996; Peng, et al., 1997), CdSe/ZnS (Kortan, et al., 1990; Hines

and Guyot-Sinnest, 1996; Dabbousi, et al., 1997), CdSe/ZnSe (Hoener, et al., 1992;
Danek, et al., 1996) have been synthesized using different methods. They showed
enhancement of photocatalytic efficiency and strong enhancement of emission.
Reversed micelle is also an important method for synthesizing the composite
nanoparticles. So far reversed micelles have been successfully used to synthesize
composite nanoparticles such as CdS-ZnS (Hirai, et al., 1994), CdS-Ag2S (Han, et al.,
1998) and CdSe-ZnS (Kortan, et al., 1990), CdSe-ZnSe (Hoener, et al., 1992).
For shell-core type nanoparticles the synthesis contains two steps: the first step is the
formation of core nanoparticles in the reverse micelles and the second step is the growth
of the shell particles on the core. CdS/ZnS (where CdS is the core and the ZnS is the
shell) is a typical shell-core type composite nanoparticles and can be synthesized as
follows. Mixing the reverse micelles containing Cd2+ and S2- in a 1 : 2 ratio, one can
obtain the core CdS reverse micelle solution. In this reversed micelle S2- is excess. After
several minutes, Zn2+ containing reverse micelle was added. ZnS precipitated in the core
CdS nanoparticles, and a shell-core type CdS/ZnS composite nanoparticle was obtained.
For the ZnS/CdS composite, the same method can be used, only changing the order of
synthesis. Using this method, Ma et al. have prepared composite nanoparticles of
CdS/ZnS and ZnS/CdS. Another type of composite nanoparticle contains two metals not
in the 1 : 1 ratio. They can be synthesized as follows. In the synthesis of coated
Ag2S/CdS nanoparticles, after mixing the two reverse micelles containing the equal
molar Cd2+ and S2-, AgNO3 was added to the mixed reversed micelles. The reaction of
2Ag+ + CdS(s) → Cd2+ + Ag2S. Coated Ag2S/CdS small particles with a diameter of ~10
nm was obtained. The nanoparticles showed large nonlinear absorption.

1.4 Synthesis
Microemulsions

of

Organic

Nanoparticles

from

O/W

1.4.1 Introduction
Only a limited number of organic nanoparticles can be prepared using oil-in-water (O/W)
microemulsions (Gan, et al., 1983a; Atik and Thomas, 1981; Leong, et al., 1984; Candau,
1990), usually called microemulsion polymerization. Stoffer and Bone (1980a, 1980b)
14

www.pdfgrip.com


first reported using O/W microemulsion in polymerization of methylacrylate and
methylmethacrylate, but found phase separation occurred during the polymerization.
Similar problems have been encountered by Gan et al. (Gan, et al., 1983a, 1983b; Gan
and Chew, 1983, 1984, 1985; Chew, et al., 1989) and Jayakrishnan (Jayakrishnan and
Shah, 1984). Phase separation is perhaps the main reason why such techniques made
little progress within the past decade (Holdcroft, et al., 1990).
Nanosize polymer particles can be obtained using polymerization reactions in O/W
microemulsions (Stoffer and Bone, 1980a, 1980b; Antonietti, et al., 1991). This leads to
hydrophobic polymer nanoparticles (10–40 nm) dispersed in water. The advantages of
this method are fast polymerization rates and high molar masses of polymers, while the
drawback is the need of high weight ratio of surfactant to monomer.
Carver (Carver, et al., 1989) studied the polymerization process using electron
microscopy and found that each polymer particle is formed in a single nucleation step,
the number of particles growing steadily during the polymerization. Figure 1.10

illustrates the polymerization mechanism in O/W microemulsions (Candau, 1990).
Figure 1.10 Schematic representation of synthesis of organic nanoparticles in
O/W microemulsions: I. Before polymerization. II. Polymer particle growth (a)
by collisions between particles, (b) by monomer diffusion through the oil phase.
III. End of polymerization (Candau, F., 1990).

Matching between oils and emulsifiers is the key to making stable latices. The particle
size depends on the nature and concentration of surfactant; usually the lower the
surfactant content, the bigger the size. The presence of electrolyte may help the
formation of stable microlatices (Holtzscherer and Candau, 1988).
1.4.2 Synthesis of Styrene Latex Nanoparticles from O/W Microemulsions
The first successful microemulsion polymerization was reported by Atik and Thomas
(1981), who used CTAB/styrene/hexanal/water O/W micro-emulsion. The reaction was
carried out either thermally using azobisisobutyronitrile (AIBN) or radiolytically using
Cs γ-ray source. Monodisperse latex nanoparticles of diameters 35 and 20 nm were
obtained, respectively.
Styrene has also been polymerized using three component microemulsions of dodecyl
trimethyl ammonium bromide (DTAB) and potassium persulphate (KPS) initiator
15

www.pdfgrip.com


(Perez-Luma, et al., 1990). This resulted in monodisperse latices with radii in the range
of 20–30 nm. Guo et al. (1989) studied styrene polymerization in SDS/pentanol/water
microemulsions using both water soluble KPS and oil soluble AMBN as initiators, and
found that the fraction of formed particles was determined by the amount of initiator.
Kuo, et al. (1987) studied photo initiated polymerization of styrene in O/W
microemulsions using dibenzyl ketone as initiator. Uniform nanosize latices were
formed. Styrene may also be polymerized in anionic (AOT) and non-ionic (Neodol 91-5

and Emsorb) microemulsions (Qutubuddin, et al., 1989). In the ionic system, gelation
took place during polymerization; while in the non-ionic system the microemulsion first
became a gel after which polymerization started. Temperature control is usually
important for nucleation and growth of the particles.
Co-polymerized styrene with divinylbenzene (DVB) in microemulsions of CTAB and
hexanol was studied by Atik and Thomas (1982). The size of spherical particles was
between 20 and 40 nm. The particles were charged, had a distinctly rigid core, and were
very stable when the latices were diluted.
1.4.3 Synthesis of Methylmethacrylate Nanoparticles from O/W Microemulsions
Styrene and methylmethacrylate (MMA) microemulsion polymerization was
investigated by Jayakrishnan (Jayakrishnan and Shah, 1984). Non-ionic surfactant
(Pluronic L-31) and the oilsoluble initiator AIBN and benzoyl peroxide (BP) were used.
However, the microemulsion systems did not remain stable during the polymerization
process. As a result, nonspherical particles with low stability were formed.
Palani Raj, et al. (1991) studied the polymerization of MMA using MMA/ethylene
glycol dimethacrylate/water systems with acylamide as amphiphile. The particles
formed were transparent up to 60% of water in the microemulsion systems.

1.5 Applications
Since the particle size of nanoparticles is in the order of nanometers (1–100 nm), both
electron distributions and atom positions at the surface may be different from those at
the bulk. Thus, nanoparticles show many outstanding characteristics that the bulk
materials do not possess. The most obvious properties are surface effect, quantum effect
(Kubo, 1962; Wang and Herron, 1991), mini-size effect and macroquantum channel
effect (Legget and Chakravarty, 1987; Awschalom and McCord, 1990). It is these
special properties that make nanoparticles attractive to many researchers, and
nanoparticles have found many novel applications in the electronic, metallurgical,
chemical, biological and pharmaceutical industries.
There are two important applications for nanoparticles prepared through microemulsion
routes. One application is the synthesis of high performance materials, such as

superconductivity materials, smart materials, coating materials for chemical or
biological sensors, etc. Another application is drug delivery systems, which may have
potential market in biomedical industries.
16

www.pdfgrip.com


1.6 Prospects
It is no dispute that nanoparticles will play an important role in the future advanced
materials and in medicine and biology. For these applications some aspects should be
addressed and could be improved. First, one needs to develop the synthesis methodology
of the nanoparticles with designed function and properties. Second one must solve the
problem of the long-term stability of nanoparticles in their applications. Finally one
should establish the strategy of assembling ordered nanoparticles in multifunctional
devices. Biocompatibility is also a key element concerning the application of
nanoparticles in biological systems.
References
Adair, J. H., R. P. Denkewicz, F. J. Arriagada and K. Osseo-Asare. (1987), CeramicTransactions,
Ceramic Powder Science II (Messing, G. L., Fuller, E. R. and Hausner, H. Eds.). American
Ceramic Society, Westerville, Ohio, 135–145
Ahmadi, T. D., Z. L. Wang, A. Henglein, M. A. El-sayed, Chem. Mater. 8, 1161 (1996a)
Ahmadi, T. D., Z. L. Wang, T. C. Green, A. Henglein, M. A. El-sayed. Science. 272, 1924
(1996b)
Antonietti, M., W. Bremser, D. Muschenborn, C. Rosenauer, B. Schupp and M. Schmidt.
Macromolecules. 24, 6636 (1991)
Arendt, R. H., J. H. Rosolowski and J. W. Szymaszek. Mat. Res. Bull. 14, 703 (1979)
Arriagada, F. J. and K. Osseo-Asare. J. Colloid Interface Sci.. 170, 8 (1995)
Atik, S. S. and J. K. Thomas. J. Am. Chem. Soc.. 104, 5868 (1982)
Atik, S. S. and J. K. Thomas. J. Am. Chem. Soc.. 103, 4279 (1981)

Awschalom, D. D. and M. A. McCord. Phys. Rev. Lett.. 65, 783 (1990)
Ayyub, P., A. N. Maitra and D. O. Shah. Physica C 168, 571 (1990)
Ayyub, P., M. Multani, M. Barma, V. R. Palker and D. O. Shah. Phys. C 21, 2229 (1988)
Bagwe R. P. and K. C. Khilar. Langmuir. 13, 6432 (1997)
Balboa, A., R. E. Partch and E. Matijevic. Colloids Surfaces. 27, 123 (1987)
Barnickel, P. and A. Wokaun. Mol. Phys.. 1990, 69, 1
Barnickel, P., A. Wokaun, and W. Sager, et al.. J. Colloid Interface Sci.. 148, 80 (1992)
Bellare, J. R., T. Kaneco and D. F. Evans. Seeing micelles, Langmuir, 4, 1066 (1988)
Berkowitz, A. E. and J. L. Walter. J. Mater. Res.. 2(2), 277 (1987)
Boalkye, E., L. R. Radovic and K. Osseo-Asare. J. Colloid Interface Sci. 163, 1209 (1994)
17

www.pdfgrip.com


Boutonnet M., J. Kizling, P. Stenius and G. Maire. Colloids Surfaces, 5, 209 (1982)
Boutonnet, M., A. N. Khan-Lodhi and T. Towey. Structure and Reactivity in Reversed Micelles
(Pileni, M. P., ed.). Elsevier, Amsterdam and New York, 198 (1989)
Candau, F.. in Scientific Methods for the Study of Polymer Colloids and Their Applications
(Candau, F. and Ottewill, R. H. (Eds.)) Kluwer Academic Publ., Dorrecht, The Netherlands,
73 (1990)
Carver, M. T., E. Hirsch, J. C. Wittmann, R. M. Fitch and F. Candau. J. Phys. Chem.. 93, 4867
(1989)
Chang C. L. and H. S. Fogler. Langmuir, 13, 3295 (1997)
Chang, S. Y., L. Liu and S. A. Asher. J. Am. Chem. Soc.. 116, 6739 (1994)
Chen J. P., K. M. Lee, C. M. Sorensen, K. J. Klabunde and G. C. Hadjipanayis. J. Appl. Phys.. 75,
5876 (1994)
Chen, Z. J., X. M. Qu, F. Q. Tang and L. Jiang. Colloids Surfaces B: Bioin-terfaces. 7, 173 (1996)
Cheng, C. P., P. A. Iacobucci and E. N. Walsh. U.S. Patent 4,619,908 to Stauffer Chemical
Company (1986)

Chew C. H., L. M. Gan and D. O. Shah. J. Dispersion Sci. Technol.. 11, 593 (1990)
Chew, C. H., L. M. Gan. K. L. Mittal (Ed.), Surfactants in Solution, Vol. 10, Plenum Press, New
York, 243 (1989)
Chhabra V., V. Pillai, B. K. Mishra, A. Morrone and D. O. Shah. Langmuir, 11, 3307 (1995)
Dabbousi, B. O., J. Rodriguez-Viejo, F. V. Mikulec, J. R. Heine, H. Mattoussi, R. Ober, K. F.
Jensen and M. G. Bawendi. J. Phys. Chem. B, 101, 9463 (1997)
Dance, G., A. Choy and M. L. Scudder. J. Am. Chem. Soc.. 102, 6285 (1984)
Danek M., K. F. Jensen, C. B. Murray and M. G. Bawendi. Chem. Mater.. 8, 173 (1996)
Dvolaitzky, M., Ober, R., Taupin, C., Anthore, R., Auvray, X., Petipas, C. and Williams, C.. J.
Dis. Sci. Tech. 29 (1983)
Eastoe, J. and B. Warne. Curr. Opin. Colloid Interface Sci.. 1, 800 (1996)
Enustun, B. V. and J. J. Turkevich. J. Am. Chem. Soc.. 85, 3317 (1963)
Esquena J., T. F. Tadros, K. Kostarelos and C. Solans, Langmuir. 13, 6400 (1997)
Frens, G.. Nature (London) Phys. Sci., 241, 20 (1973)
Gan L. M., K. Zhang and C. H. Chew. Colloids Surfaces. A, 110, 199 (1996)
Gan, L. M., C. H. Chew and S. E. Friberg. J. Polym. Sci., Polym. Chem. Ed., 21, 513 (1983a)
Gan, L. M. and C. H. Chew. J. Disp. Sci. Technol.. 4, 291 (1983)
Gan, L. M. and C. H. Chew. J. Disp. Sci. Technol.. 5, 179 (1984)
18

www.pdfgrip.com


Gan, L. M. and C. H. Chew. J. Polym. Sci., Polym. Chem. Ed., 23, 2225 (1985)
Gan, L. M., C. H. Chew and S. E. Friberg. J. Macromol. Sci., Chem.. A, 19, 739 (1983b)
Gobe, M., K. K. No, K. Kanori, and A. Kitahara. J. Colloid Interface Sci.. 93(1), 293 (1983)
Gopidas K. R., M. Bohorquez and P. V. Kamat. J. Phys. Chem.. 94, 6435 (1990)
Gordon, L., M. L. Salutsky and H. H. Willard. In. Precipitation from Homogeneous Solution.
John Wiley, New York. (1959)
Guo, J. S., El-Aasser and W. J. Vanderhoff. J. Poly., Sci., Polym. Chem. Ed., 27, 691 (1989)

Gutmann, H. and A. S. Kertes. J. Colloid Interface Sci.. 51, 406 (1973)
Han, M. Y., W. Huang, C. H. Chew, L. M., Gan, X. J. Zhang and W. Ji. J. Phys. Chem. B, 102,
1884 (1998)
Haram S. K., A. R. Mahadeshwar and S. G. Dixit. J. Phys. Chem.. 100, 5868 (1996)
Hasselbarth A., A. Eychmuller, R. Eichberger, M. Giersig, A. Mews and H. Weller. J. Phys.
Chem.. 97, 5333 (1993)
Herron, N., Y. Wang and H. Eckert. J. Am. Chem. Soc.. 112, 1322 (1990)
Hines, M. A. and P. Guyot-Sinnest. J. Phys, Chem.. 100, 468 (1996)
Hirai, T., S. Shiojiri and I. Komasawa. J. Chem. Eng. Jpn., 27, 590 (1994)
Hoar, T. P. and J. H. Schulman. Nature. 152, 102 (1943)
Hoener C. F., K. A. Allan, A. J. Bard, A. Campion, M. A. Fox, T. E. Mallouk, S. E. Webber and
J. M. White. J. Phys. Chem.. 96, 3812 (1992)
Holdcroft, Y. S. and J. E. Guillet. J. Polym. Sci., Polym. Chem. Ed.. 28, 1823 (1990)
Holtzscherer, C. H. and F. Candau. J. Colloid Interface Sci.. 125, 97 (1988)
Hopwood, J. D. and S. Mann. Chem. Mater.. 9, 1819 (1997)
Hou, M. J. and D. O. Shah, In: Interfacial Phenomena in Biotechnology and Materials Processing
(Attia, Y. A., Mouggil, B. M. and Chander, S., eds.). Elsevier, Amsterdam, 443 (1988)
Israelachvili, J. N., D. J. Mitchell and B. W. Ninham. J. Chem. Soc.. Faraday Trans. I, 72, 1525
(1976)
Israelachvili, J. N.. Physical principles of surfactant self-association into micelles, vesicles and
microemulsion droplets. In: Surfactants in Solution. Mitall, K. L., Bothorel, P., (Eds.),
Plenum, New York, Vol. 4, 3 (1985)
Iwama, S., K. Hayakawa and T. J. Arizumi. Crys. Growth 56, 265 (1982)
Jayakrishnan, A. and D. O. Shah. J. Polym. Sci., Polym. Lett. Ed., 22, 31 (1984)
Joselevich E. and I. Willner. J. Phys. Chem.. 98, 7628 (1994)
19

www.pdfgrip.com

Kagawa, M., M. Kikuchi and Y. Syono. J. Am. Ceram. Soc. 66(1), 751 (1983)
Kamalov V. F., R. Little, S. L. Logunov and M. A. El-Sayed. J. Phys. Chem.. 100, 6381 (1996)
Kandori K., K. Kon-No and A. Kitahara. J. Colloid Interface Sci., 122, 78 (1987)
Kandori K., K. Kon-No and A. Kitahara. J. Dispersion Sci. Technol., 9, 61 (1988)
Karayigitoglu C. F., M. Tata, V. T. John and G. L. McPherson. Colloids Surfaces. A, 82, 151
(1994)
Kato, S., H. Nomura and H. Honda. J. Phys. Chem.. 92, 2305 (1988)
Kawai T., A. Fujino and K. Kon-No. Colloids Surfaces. A, 100, 245 (1996)
Kertes, A. S. and H. Gutmann. In: Surface and Colloid Science. Vol. 8, p. 194, Wiley, New York,
(1976)
Kon-no, K. In: Fine Particles Science and Technology (E. Pelizzetti, ed.), Kluwer Academic. 431
(1996)
Kortan A. R., R. Hull, R. L. Opila, M. G. Bawendi, M. L. Steigerwald, P. J. Carroll and L. E.
Brus. J. Am. Chem. Soc., 112, 1327 (1990)
Krafft, F.. Ber. Deutsch. Chem. Gesell. 32, 1596 (1899)
Kubo, R.. J. Phys. Soc. Japan., 17, 975 (1962)
Kuo, P. L., N. J. Turro, C. M. Tseng, M. S. El-Aasser and J. W. Vanderhoff. Macromolecules. 20,
1216 (1987)
Lawless D., S. Kapoor and D. Meisel. J. Phys. Chem., 99, 10329 (1995)
Legget, A. J. and S. Chakravarty. Rev. Phys. Chem., 59, 1 (1987)
Leong, Y. S., S. F. Candau and F. Candau. In: Mittal, K. L. and Lindman, B. (Eds.), Surfactants
in Solution. Vol. 3. Plenum Press, New York, 1897 (1984)
Leung, R., M. Jeng, Hou and D. O. Shah. In: Wasan, D. T., Ginn, M. E. and Shah, D. O. (Eds.),
Surfactants in Chemical Process Engineering, Surfactant. Sci. Ser. Vol. 28. Marcel Dekker,
New York, 315 (1988)
Lianos P. and J. K. Thomas. J. Colloid Interface Sci.. 117, 505 (1987)
Lindman, B., H. Wennerstraom and H. F. Eicke. Micelles, Springer-Verlag, Heidelberg (1980)
Lisiecki I. and M. P. Pileni. J. Am. Chem. Soc.. 115, 3887 (1993)
Lisiecki I. and M. P. Pileni. J. Phys. Chem.. 99, 5077 (1995)
Liu, J., A. Y. Kim, L. Q. Wang, et al.. Adv. Colloid Interface Sci.. 69, 131 (1996)

Liz, L., M. A. Lopez-Quintela, J. Mira and J. Rivas. J. Mater. Sci., 29, 3797 (1994)
Lopez-Perez J. A., M. A. Lopez-Quintela, J. Mira, J. Rivas and S. W. Charles. J. Phys. Chem.. B,
101, 8045 (1997)
20

www.pdfgrip.com