New Types of Emulsions

Phase behavior (left) and interfacial tension (right) of water/tetradecane/Ci2Es mixtures 

The finely-dispersed nature of the microemulsion is partially retained after cool-ing. Emulsions with particle sizes of about 100 nm exhibit long-term stability simply as a consequence of the Brownian motion of the oil droplets,so that low-viscosity, sprayable emulsions can also be produced. Pump-type milky deodorant emulsions are one of the cosmetic product innovations based on this process. 

The PIT phenomenon is predictable by parameters. With the help of characteristic variables for oil and emulsifiers, new formulations with desired components can be calculated on a computer by means of the CAPICO procedure (calculation of phase inversion in concentrates), so that development times can be dramatically reduced.  

Microemulsions have been the subject of intensive research efforts for many years. This research has been concentrated above all on microemulsions with ethoxylated nonionic surfactants. However, these microemulsions have not yet been able to establish themselves on the market. The main reason is probably the very high concentrations of surfactants—often in combination with large amounts of short-or long-chain alcohols —that are needed to obtain stable microemulsions. This results in high raw material costs and can have a negative effect on skin compatibility. 

The alkyl polyglycosides (APGs) form a new class of nonionic surfactant that are characterized by their excellent environmental and dermatological compatibil-ity. Combinations of alkyl polyglycosides with certain hydrophobic cosurfactants are extremely effective in expediting the formation of stable microemulsions.  

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Melzer E, Kreuter J, Daniels R. Ethylcellulose A new type of emulsion stabilizer. Eur J Pharm Biopharm 2003 56 23—27. 

E Melzer, J Kreuter, R Daniels, Ethylcellulose a new type of emulsion stabilizer , EurJPfuarm Biopharm, 2003 56 23-27... 

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