Nanoparticles using microemulsions

Xin et al. [10] evaluated the synthesis of catalyst nanoparticles using microemulsions like cyclohexane. In this work no pure metal were observed, only alloys of the catalyst exhibited as seen from X-ray diffraction (XRD). The composition and particle was controlled using microemulsions [11,12]. The alloy formation of platinum, which has a FCC structure, included shifting of the diffraction peak to a higher angle (20), indicating a decrease in lattice parameter. 

Li, Y. and Park, C.-W. 1999. Particle size distrihution in the synthesis of nanoparticles using microemulsions. Langmuir, 15, 952-956. 

Preparation of silica-coated Pt-Ni alloy nanoparticles using microemulsions and formation of carbon nanofibers by ethylene decomposition... 

FIG. 18 Formation of nanoparticles using microemulsions (water-in-oil) as nanoreactors. The water droplets continually collide, coalesce, and break up upon mixing of two microemulsions containing reactants. 

Core-shell nanoparticles can also be fabricated using microemulsions. This was performed using a two-stage microemulsion polymerization beginning with a polystyrene seed [62]. Butyl acrylate was then added in a second step to yield a core-shell PS/PBA morphology. The small microlatex led to better mechanical properties than those of similar products produced by emulsion polymerization. Hollow polystyrene particles have also been produced by microemulsion polymerization of MMA in the core with crosslinking of styrene on the shell. After the synthesis of core-shell particles with crosslinked PS shells, the PMMA core was dissolved with methylene chloride [63]. The direct cross-... 

Fig. 13 Synthesis of nanoparticles in microemulsions using a double inverse microemulsions b inverse microemulsion plus a trigger c inverse microemulsion plus reactant [122]...

Figure 11 illustrates the formation of metallic nanoparticles using reverse microemulsions as an example of growing particles within individual dispersed phases or molecular containers. In this process, a metal salt is solubilized in the aqueous interior of... 

Husein, M.M., Rodil, E. and Vera, J.H. (2005) A novel method for the preparation of silver chloride nanoparticles starting from their solid powder using microemulsion. /. Colloid Interface Sci., 288, 457M67. 

Apart from the already established formulations, researchers are trying to develop novel oil-based formulations to combat the poor solubility and bioavailablity of NCE. Shevachman et al. developed novel U-type microemulsions to improve the percutaneous permeability of diclofenac. Shah et al.2 2 used microwave heating for the preparation of solid lipid nanoparticles by microemulsion techniques, which resulted in improved particle characteristics. Ki et al. reported sustained-release liquid crystal of injectable leuprolide using sorbitan monooleate. Recently, various novel oil-based drug delivery technologies are reported, which includes tocol emulsions, solid lipid nanopar-ticles, nanosuspensions, Upid microbubbles, sterically stabilized phospholipid micelles, and environmentally responsive drug delivery systems for parenteral administration.25 259... 

In the mid-1970s S. Friberg and the late F. Gault proposed an original method using microemulsions to prepare monodisperse nanosized particles. These ideas were followed by a rapid increase in original research works related to the preparation of metal and metal boride nanoparticles [1-5]. 

Table 3 Amounts of Doxorubicin Incorporated into Nanoparticles Using Different Concentrations of the Drug in Ethylene Glycol as the Disperse Phase of the Microemulsion...

A microemulsion is a thermodynamically stable, optically clear dispersion of two immiscible liquids such as water and oil, stabilized by the presence of a surfactant and, in some cases, a co-surfac-tant.i i7i,265-267 synthesis of nanoparticles by microemulsions has two main advantages. On the one hand, particle size can be controlled by adjusting the size of the micelle containing the metal precursors. Therefore, thermal treatments for particle size control can be avoided. On the other hand, since the micelles have the same composition, i.e. metal precursors are distributed homogeneously the nucleation of metallic particles renders particles of the same composition. This latter feature is very important for the synthesis of bimetallic (or ternary) catalysts. The main drawback of the microemulsion, or any other approach using surfactants, is surfactant removal. Severe thermal treatments are required in order to achieve complete removal of the surfactant which may result in particle aggregation and/or surface enrichment, or complete phase segregation of the components of the bimetallic samples. ... 

PUlai, V, Kumar, P, Multani, M.S., Shah, D.O. Structure and magnetic properties of nanoparticles of barium ferrite synthesized using microemulsion processing. CoU. Surf. A 80, 69-75 (1993)... 

Considering that the conventional gathering of nanoparticles from microemulsions is difficult, tedious and not remunerative due to limited quantity, Bonini etal. [230] developed a flame spraying technique for microemulsions with gold nanoparticles. The process is reminiscent of the emulsion combustion technique of Tani et al. [172, 173], but has been used for deposition of nanostructured coatings on substrates. 

Haram et al. [385] described a detailed system for the synthesis of CuS nanoparticles using a copper-ammonia complex (pH=l 1) and thiourea in separate microemulsions formed by a non-ionic surfactant (e.g. Triton X-100) with 2-methylpropan-l-ol as co-surfactant and cyclohexane as the oil phase. Other nonionic surfactants used were NP-4, NP-7 and NP-9.5 (nonylphenyl ether surfactant series) the only ionic surfactant used was sodium dodecyl sulfate (SDS). The reactions envisaged were... 

Little information is available on microemulsion-mediated synthesis of rhodium particles. Considering the importance of Rh nanoparticles in catalytic reactions, Kishida et al [426] developed a method using microemulsions. The reverse micelle was prepared with the surfactant NP-5 and cyclohexane as the continuous phase. An aqueous solution of rhodium chloride was solubilized in the micelle and hydrazine directly added to it at 25°C. The average particle size of rhodium thus obtained was about 3 nm. Kishida et al. [427] later extended the method to the use of a variety of non-ionic and ionic surfactants (C-15, i.e. polyoxyethylene(15)cetyl ether, L-23, i.e. polyoxyethylene(23)lauryl ether, NP-5 and NaAOT), as also cyclohexane or 1-hexanol (according to necessity) as the continuous phase. The reactants remained the same, i.e. rhodium chloride and hydrazine hydrate. In addition, the rhodium particles thus synthesized were coated with silica via hydrolysis-polycondensation of tetraethyl orthosilicate. The size of Rh varied in the range 1.5-4.0 nm in a typical case, a 4 nm particle was covered with a 14 nm thick layer of silica. 

A report in the same line [380] involves suspension of ZnS.Mn nanoparticles in microemulsions, with the surface modified by polyoxyethylene(l)laurylether phosphoric acid or polyoxyethylene(4.5)laurylether acetic acid. The coated particles exhibited several times higher photoluminescence intensity and quantum efficiency compared to the uncoated ones. The phosphate group P = O or the carboxyl group C = O, with their luminescent centers, were functional in this improvement, thus opening new routes for imparting superior optical properties on microemulsion-synthesized particles. Gan etaL [376] used four routes for the synthesis of ZnS Mn (i) the relatively new route that involved hydrothermal... 

Zielinska-Jurek A, Reszczynska J, Grabowska E, Zaleska A (2012) Nanoparticles preparation using microemulsion systems. In Najjar R (ed) Microemulsions - an introduction to properties and applications. InTech, Rijeka, pp 229-250... 

The computer simulation of the formation of nanoparticle in microemulsions was carried out using the model previously reported [7-9]. Briefly, each simulation began with a random... 

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