Emulsions preparation methods

Some of the above emulsion preparation methods are also used as tests of the effectiveness of different surfactants in stabilizing emulsions. For example, the... 

The soapless seeded emulsion copolymerization method was used for producing uniform microspheres prepared by the copolymerization of styrene with polar, functional monomers [115-117]. In this series, polysty-rene-polymethacrylic acid (PS/PMAAc), poly sty rene-polymethylmethacrylate-polymethacrylic acid (PS/ PMMA/PMAAc), polystyrene-polyhydroxyethylmeth-acrylate (PS/PHEMA), and polystyrene-polyacrylic acid (PS/PAAc) uniform copolymer microspheres were synthesized by applying a multistage soapless emulsion polymerization process. The composition and the average size of the uniform copolymer latices prepared by multistage soapless emulsion copolymerization are given in Table 11. 

PS/PHEM A particles in micron-size range were also obtained by applying the single-stage soapless emulsion copolymerization method [124]. But, this method provided copolymer particles with an anomalous shape with an uneven surface. PS or PHEMA particles prepared by emulsifier-free emulsion polymerization were also used as seed particles with the respective comonomer to achieve uniform PS/PHEMA or PHEMA/PS composite particles. PS/PHEMA and PHEMA/PS particles in the form of excellent spheres were successfully produced 1 iLitm in size in the same study. 

Uniform macroporous polymer particles have been prepared in the size range of 5-20 iitm by the multistage emulsion polymerization methods. Several methods are available in the literature describing the synthesis and the properties of macroporous uniform particles. The main steps of these methods may be summarized as follows. 

The preparation of microspheres can be accomplished by either of two methods thermal denaturation, in which the microspheres are heated to between 95 and 170°C, and chemical crosslinking with glutaraldehyde in a water-in-oil emulsion. Well-defined microspheres can be easily prepared using these methods in large batches which are usually physically and chemically stable. Newer preparation methods for the preparation of albumin microspheres have been described by several authors (84-88). 

PtRu nanoparticles can be prepared by w/o reverse micro-emulsions of water/Triton X-lOO/propanol-2/cyclo-hexane [105]. The bimetallic nanoparticles were characterized by XPS and other techniques. The XPS analysis revealed the presence of Pt and Ru metal as well as some oxide of ruthenium. Hills et al. [169] studied preparation of Pt/Ru bimetallic nanoparticles via a seeded reductive condensation of one metal precursor onto pre-supported nanoparticles of a second metal. XPS and other analytical data indicated that the preparation method provided fully alloyed bimetallic nanoparticles instead of core/shell structure. AgAu and AuCu bimetallic nanoparticles of various compositions with diameters ca. 3 nm, prepared in chloroform, exhibited characteristic XPS spectra of alloy structures [84]. 

The coacervation approach uses heating or chemical denaturation and desolvation of natural proteins or carbohydrates. As much as 85% of water-soluble drugs can be entrapped within a protein matrix by freeze-drying the emulsion prepared in this manner. For water-insoluble drugs, a microsuspension-emul-sion procedure has been suggested as a method of choice to achieve high drug payloads. 

Izquierdo, P., Esquena, J., Tadros, T.F., Dederen, C., Garcia, M.J., Azemar, N. and Solans, C. (2002) Formation and stability of nano-emulsions prepared using the phase inversion temperature method. Langmuir, 18 (1), 26-30. 

Sole, I., Maestro, A., Gonzalez, C., Solans, C. and Gutierrez, J.M. (2006) Optimization of nano-emulsion preparation by low-energy methods in an ionic surfactant system. Langmuir, 22 (20), 8326-8332. 

Figure 6. Preparation scheme for the emulsion-evaporation method.

Figure 10.4 (Plate 8) Polystyrene spheres prepared by emulsion polymerization methods. Because they may be packed together to form columns or beds, these spheres find applications in separations, ion exchange, and as supports for catalysts. (Photographs by John Olive)...

P. Izquierdo, J. Esquena, T.F. Tadros, J.C. Dederen, M.J. Garcia, N. Azemar, and C. Solans Formation and Stability of Nano-Emulsions Prepared Using the Phase Inversion Method. Langmuir 18, 26 (2002). 

R. Pons, I. Carrera, P. Erra, H. Kunieda, and C. Solans Novel Preparation Methods for Highly Concentrated Water-in-Oil Emulsions. Colloids Surf., A Physicochem. Eng. Asp. 91, 259 (1994). 

J.M.J. Bibette, E. Leal-Calderon, and P. Gorria Polydisperse Double Emulsion, Corresponding Monodisperse Double Emulsion and Method for Preparing the Monodis-perse Emulsion. Patent WO 2001021297 (2001). 

The oils were applied in the form of an aqueous emulsion prepared according to the tank-mixture method. Most of the time it is possible to approach a given oil deposit by proper adjustment of the concentration of oil in the spray mixture. The volume basis was used for the concentration of oil in the spray emulsion. The ingredients were emulsified and agitated by means of a high speed homomixer (made by Eppenbach, Inc., Long Island City, N. Y.). 

Monodisperse emulsions, prepared by the double-jet method, have a narrow range of grain sizes of uniform shape. The grains can be either cubic or octahedral, depending on the conditions of preparation. 

Surface image is formed predominantly in monodisperse, fine-grain emulsions prepared by the double-jet method. 

Various electron microscopy techniques have been used to study the structures of whippable emulsions such as normal and cryo-scanning electron microscopy or transmission electron microscopy using various preparation methods such as freeze fracturing, freeze etching, etc. The literature is quite extensive, and only a few important papers will be discussed in this chapter. 

The traditional methods of emulsion preparation, especially those involving stirring and shaking, tend to lead to uncontrolled and wide drop-size distributions. Several methods for the preparation of fairly monodisperse emulsions exist, of which the simplest is probably the extrusion of a dispersed phase through a pipette into a flowing continuous phase. Other, more involved methods are discussed by Mason [433],... 

In the early 1990s, Nakashima et al. [2] introduced membrane technology in emulsions preparation by a direct emulsification method, whereas, in the late 1990s, Suzuki et al. used premix membrane emulsification to obtain production rates higher than other membrane emulsification methods [11]. 

In order to simplify the previous preparation method, a more straightforward procedure was later developed by the same group [30], The polymerization mixture consisted of an aqueous solution of acrylamide A, piperazine diacrylamide 111, and vinylsulfonic acid 12 with added stearyl methacrylate 2 or butyl methacrylate 1A to control the hydrophobicity of the gel. Since neither of these non-polar monomers is soluble in water, a surfactant was added to the mixture, followed by sonication to form an emulsion of the hydrophobic monomer in the aqueous solution. Once initiated, the mixture was immediately drawn into an acryloylsilanized capillary, where the polymerization was completed. The presence of the strongly acidic sulfonic acid functionalities afforded EOF that remained constant over a broad pH range. 

Of the various methods of latex preparation known and practiced, a variant of the emulsion-addition method was chosen for further investigation because the reaction temperature is easy to control and coagulum... 

Preparation Methods for Drug-Free/Loaded Oil-in-Water Nanosized Emulsions... 

PREPARATION METHODS FOR DRUG-FREE/LOADED OIL-IN-WATER NANOSIZED EMULSIONS... 

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