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Emulsion-Derived Foams Preparation, Properties, and Application

Published online by Cambridge University Press:  29 November 2013

William R. Even Jr.  and
Donald P. Gregory
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Extract

Porous polymeric foams are well-known materials and have been produced by a wide variety of techniques ranging from leaching soluble fillers through gas-blowing to phase separation. Although these materials are widely used, their structure is often irregular and difficult to control. However, a novel method for producing porous materials with a more regular structure has been developed based on high internal phase emulsions (HIPE). These foams are called emulsion-derived foams and are commercially known as Polyhipe® (Unilever) polymers.

If one takes a liquid oil, introduces water and a suitable emulsifier with agitation, a dilute emulsion is produced with small water droplets dispersed within the oil phase, about the consistency of milk. If the amount of the water (i.e., the internal or pore forming) phase is increased, a concentrated emulsion will be formed and the consistency of the mixture changes into a more viscous fluid. As further water is introduced, a limit is reached where the droplets are so prevalent that they approximate a close-packed structure (see cover of this issue); beyond this point the droplets must distort to accommodate any additional internal phase. For a collection of monodispersed spheres this packing limit corresponds to 74% by volume and is the accepted definition of a high internal phase emulsion, i.e., an emulsion with an internal phase greater than 74%.4 The structure of the emulsion is now analogous to soap bubbles, with thin films surrounding and separating the drops. Note also that, compared to “standard” emulsion polymerization, this is the exact reverse or “inverse” of that process. In the standard route, the dispersed oil phase is polymerized to yield a collection of polymeric spheres; with inverse emulsion, the continuous phase is polymerized, yielding a rigid matrix.

Type
Engineered Porous Materials
Information
MRS Bulletin , Volume 19 , Issue 4 , April 1994 , pp. 29 - 33
Copyright
Copyright © Materials Research Society 1994

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References

1.Barby, Donald and Haq, Zia, U.S. Patent No. 4,552,953 (June 11, 1985).Google Scholar
2.Haq, Zia, U.S. Patent No. 4,536,521 (August 20, 1985).Google Scholar
3.Jones, Keith, Lothian, Barry, Martin, Alexander, Taylor, Graham, and Haq, Zia, U.S. Patent No. 4,611,014 (September 9, 1986).Google Scholar
4.Lissant, K.J., in Emulsions and Emulsion Technology, Vol. 6, Part 1, edited by Lassant, K.J. (Marcel Dekker Publishing, New York 1974) p. 49.Google Scholar
5.Gregory, D.P., Sharpies, M., Edwards, C.J.C., and Warner, M., unpublished data.Google Scholar
6.Shaw, M.C., Sata, T., Int. J. Mech. Sci. 8 (1966) p. 469.CrossRefGoogle Scholar
7.Kurachi, T., Sato, N., Kamiguito, O., and Komatastu, N., J. Mater. Sci. 19 (1984) p. 871.CrossRefGoogle Scholar
8.Ermolenko, I.N., Lyubliner, I.P., and Gulko, N.V., in Chemically Modified Carbon Fibers and Their Applications, translated by Titovets, E.P., (VHC Publishing, New York, 1990) p. 3.Google Scholar
9.Edwards, Christopher, Hitchen, David, and Sharpies, Martin, U.S. Patent No. 4,755,655 (October 4, 1988).Google Scholar
10.LeMay, J.D., Hopper, R.W., Hrubesh, L.W., and Pekala, R.W., MRS Bulletin xv (12) (1990) p. 37.Google Scholar
11.Fitzer, E., Frohs, W., and Heine, M., Carbon, 24 (1986) p. 387.CrossRefGoogle Scholar
12.Bashir, Z., Carbon, 29 (1991) p. 1081.CrossRefGoogle Scholar
13.Dahn, J.R., Sleigh, A.K., Hang, S., Reimers, J.N., Zhong, Q., and Way, B.M., Electrochem. Acta 38 (1993) p. 1179.CrossRefGoogle Scholar
14.Kinoshita, K., in Carbon, Electrochemical and Physicochemical Properties (John Wiley and Son, New York, 1988) p. 115.Google Scholar
15.Small, P.W. and Sherrington, D.C., J. Chem. Soc. Chem. Commun. (1989) p. 1589.CrossRefGoogle Scholar
16.Gregory, D.P., Bhaskar, N., Sheppard, R.C., and Singleton, S., in Solid Phase Synthesis, Collected Papers of Second International Sym., edited by Epton, R. (Intercept, Andover U.K. 1992) p. 361.Google Scholar