Nano-emulsion formation by low energy

Nano-Emulsion Formation by Low-Energy Methods and Functional Properties... 

In this chapter, nano-emulsion formation by low-energy emulsification methods, with special emphasis on phase inversion methods and their relation to surfactant phase behavior will be discussed first. This will be followed by an analysis of nano-emulsion functional characteristics. The relation with their structure is discussed regarding the applications in which they are relevant. Prior to discussing nano-emulsion functional characteristics, the main nano-emulsion destabilization mechanism, Ostwald ripening, is described. 

Forgiarini, A., Esquena, J., Gonzalez, C. and Solans, C. (2001) Formation of nano-emulsions by low-energy emulsification methods at constant temperature. Langmuir, 17 (7),... 

Sadurm, N., Solans, C., Azemar, N. and Garci a-Celma, M.J. (2005) Studies on the formation of O/W nano-emulsions, by low-energy emulsification methods, suitable for pharmaceutical aplications. Emulsion polymerization initiation of polymerization in monomer droplets., 26, 438-445. 

In this chapter, different methods for nano-emulsion formation, with special emphasis on low-energy emulsification methods, are discussed in Section 11. This is followed by a description of nano-emulsion stability (Section 111). Finally, the most relevant applications of nano-emulsions are reviewed... 

Considering only mechanical energy aspects, nano-emulsion formation should be considerably costly. However, it is well known that by taking advantage of the physicochemical properties of the system, dispersions can be produced almost spontaneously [3,6,14]. This is the case with the so-called low-energy emulsification methods that are described next. In practice, the two types of methods are often combined. 

Caldero, G., Garcfa-Celma, M.J. and Solans, C. (2011) Formation of polymeric nano-emulsions by a low-energy method and their use for nanoparticle preparation. Journal of Colloid and Interface Science, 353, 406-411. 

N. Uson, MJ. Garcia, and C. Solans Formation of Water-in-Oil (W/O) Nano-Emulsions in a Water/Mixed Non-Ionic Surfactant/Oil Systems Prepared by a Low-Energy Emulsification Method. Colloid and Surfaces A Physicochem. Eng. Aspects 250, 415 (2004). 

Uson, N., Garcia, M.J., and Solans, C., Formation of water-in-oil (W/O) nano-emulsions in a water/ mixed non-ionic surfactant/oil systems prepared by a low-energy emnlsification method, Colloids Surf. A Physicochem. Eng. Aspects, 2004, 250(1-3), 415 21. 

Nano-emulsions are defined as a class of emulsions with uniform and extremely small droplet size (typically in the range 20-500 nm). The formation of kinetically stable liquid/hquid dispersions of such small sizes is of great interest from fundamental and applied viewpoints. In this review, nanoemulsion formation, with special emphasis on low-energy emulsification methods, is first discussed. This is followed by a description of nano-emulsion properties, focusing on their kinetic stability. Finally, relevant industrial applications of nano-emulsions in the preparation of latex particles, in personal-care formulations, and as drug dehvery systems are reported. 

Microemulsions form spontaneously and exhibit nano-disperse structures. In contrast to emulsions there is no additional energy input necessary for the production of a microemulsion. The formation is thermodynamically favoured due to the ultra-low interfacial tension between the oil and water domains. The microemulsified fuels are in principle thermodynamically stable for an unlimited period of time only the chemical stability of the single components could be a limiting factor. A further advantage of microemulsions in contrast to emulsions is the fact that the water content can be adjusted over a broad range. Therefore, the combustion process can be customised to specific needs. An important criterion for a microemulsion to be used as fuel is that the one-phase region extends over a wide temperature range (Fig. 11.4). Mixtures of ionic and non-ionic surfactants, which exhibit almost temperature-invariant phase behaviour by optimal composition, are suitable to meet these standards. 

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