Microchannels emulsification

Figure 1.2. Schematic principle of microchannel emulsification, (a) Top view (b) side view.

More complex geometries have been developed [40] and the influence of the geometrical structure has been examined. Although straight-through microchannel emulsification has been developed [39,41], the production rates are still low compared to those obtained with standard emulsification methods. However, the very high monodispersity makes this emulsification process very suitable for some specific fechnological applicafions such as polymeric microsphere synfhesis [42,43], microencapsulation [44], sol-gel chemistry, and electro-optical materials. 

Membrane emulsification allows a precise control of the droplet size and monodispersity but the scale up of this process is difficult. MicroChannel emulsification is a promising technique but the low production rates restrict its use to highly monodisperse systems intended for high-technology applications. 

S. Sugiura, M. Nakajima, N. Kumazawa, S. Iwamoto, and M. Seki Characterization of Spontaneous Transformation-Based Droplet Formation During MicroChannel Emulsification. J. Phys. Chem. B 106, 9405 (2002). 

I. Kobayashi, M. Nakajima, and S. Mukataka Preparation Characteristics of Oil-in-Water Emulsion Using Differently Charged Surfactants in Straight-Through MicroChannel Emulsification. Colloid Surfaces A Physicochem. Eng. Aspects 229, 33 (2003). 

S. Sugiura, M. Nakajima, and M. Seki Prediction of Droplet Diameter for MicroChannel Emulsification Prediction Model for Complicated MicroChannel Geometries. Ind. Eng. Chem. Res. 43, 8233 (2004). 

S. Sugiura, M. Nakajima, H. Itou, and M. Seki Synthesis of Polymeric Microspheres with Narrow Size Distributions Employing MicroChannel Emulsification. Macromol. Rapid Commun. 22, 773 (2001). 

K. Nakagawa, S. Iwamoto, M. Nakajima, A. Shono, and K. Satoh MicroChannel Emulsification Using Gelation and Surfactant-Free Coacervate Microencapsulation. J. Colloid Interface Sci. 278, 198 (2004). 

Chuah, A.M., Kuroiwa, T., Kobayashi, I., Nakajima, M. (2009). Effect of chitosan on the stability and properties of modified lecithin stabilized oil-in-water monodisperse emulsion prepared by microchannel emulsification. Food Hydrocolloids, 23, 600-610. 

Xu, Q.Y., Nakajima, M., and Binks, B.P. (2005). Preparation of particle-stabilized oil-in-water emulsions with the microchannel emulsification method. Colloids Surf. A, Physicochem., Eng. Aspects, 262(1-3), 94-100. 

Dekkers, K.S. (2003). Production of double emulsions by microchannel emulsification, MSc thesis. Wageningen University and Technische Universitat Karlsruhe. 

Kobayashi, I., Nakajima, M., Nabetani, H., Kikuchi, Y., Shohno, A., and Satoh, K. (2001). Preparation of micron-scale monodisperse oil-in-water microspheres by microchannel emulsification. JAOCS 78(8), 797-802. 

Fig. 7.11 Schematic of the straight through" microchannel emulsification system [138].

N ew opportunities and future directions in the area of microchannel emulsification are most likely in the areas of scale-up [140,141], encapsulation/polymeriza-tion [123, 125, 158, 164—169], rapid quenching of droplets [135], and the use of emulsions as templates for uniform macroporous particle structure formation [172]. MicroChannel emulsification is also likely to open up new opportunities with systems that are highly shear-sensitive [120, 135, 173]. The ability to scale up the process will spur new markets that require high production rates and the production of monodisperse capsules and polymer particles. Such developments will be useful in drug delivery applications and will contribute to the further quantification of micro-particle properties. Additionally, the use of monodisperse emulsions as particle templates is likely to enhance the utility of highly functional nanoparticles in need of a deployment mechanism [172]. 

Sugiura S, Nakajima M, Seki M (2002) Effect of channel structure on microchannel emulsification. Langmuir 18(15) 5708-5712... 

FIGURE 32.9 Schematic diagram of different emulsification processes to produce gel particles (a) mechanical stirring (b) static mixing (c) membrane emulsification and (d) microchannel emulsification. 

A number of approaches have been proposed for a continuous emulsification and improved control of product size distribution static mixers, membrane emulsification, and microchannel emulsification. For the last two, emulsions are produced by extruding a liquid through many individual pores or microchannels. 

Van Dijke KC, Schroen CGPH, Boom RM (2008) MicroChannel emulsification from computational fluid dynamics to predictive analytical model. Langmuir 24(18) 10107-10115... 

Kawakatsu T, Kikuchi U, Nakajima M (1997) Regular-sized cell creation in microchannel emulsification by visual microprocessing method. J Am Oil Chem Soc 74(3) 317-321... 

FIGURE 16.22 Influence of emulsification method on droplet size distribution (disperse phase content (p Ri 1 vol% emulsion formulation as in Figure 16.15. MF, microfluidization ME, membrane emulsification MC, microchannel emulsification. (From Vladisavljevic, G.T., Lambrich, U., Nakajima, M., and Schubert, H., Colloid Surface A, 232 (2-3), 199-207, 2004. With permission.)... 

Kobayashi, I., Nakajima, M., and Mukataka, S., Preparation characteristics of oil-in-water emulsions using differently charged surfactants in straight-through microchannel emulsification, Colloid Surfaces A, 229 (1-3), 33-41, 2003. 

Sugiura, S., Nakajima, M., Kumazawa, N., Iwamoto, S., and Seki, M., Characterization of spontaneous transformation-based droplet formation during microchannel emulsification, J. Phys. Chem. B, 106, 9405-9409, 2002. 

S. Sugiura, M. Nakajima, J.H. Tong, H. Nabetani, M. Seki, Preparation of monodispersed solid lipid microspheres using a microchannel emulsification technique./oumoJ of Colloid and Interface Science, 2000, 227, 95-103. 

Kobayashi, S. Mukataka, M. Nakajima, Effects of type and physical properties of oil phase on oil-in-water emulsion droplet formation in straight-through microchannel emulsification, experimental and CFD studies, Langmuir, 2005, 21, 5722-5730. 

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