Krafft Points and Cloud Points of Polyoxyethylated Nonionic Surfactants
-
H. Schott
Abstract
The solubility of polyoxyethylated nonionic surfactants (POSs) in water is limited by an upper and a lower critical temperature. The former, called cloud point (CP), is the temperature at which POSs precipitate from solution on heating because of excessive dehydration of their polyoxyethylene (POE) moieties. The latter, called Krafft point (KP), is the temperature at which POSs crystallize from solution on cooling because of increased alignment and attraction between their hydrocarbon chains. It occurs less frequently: Even if the POSs were capable of crystallizing, ice often crystallizes first.
Aqueous solutions of over 100 POSs were examined by obtaining their CPs and ascertaining whether they exhibit KPs. KPs were found in polyoxyethylated primary alcohols and fatty acid amides and in polyethylene glycol esters of fatty acids. Only surfactants with strictly linear hydrocarbon chains crystallize, exhibiting KPs. Any branching, including that in polyoxyethylated linear secondary alcohols, prevents crystallization. Crystallization only occurs when the number mof carbon atoms in the hydrocarbon chains equals or exceeds 12. The KPs are then proportional to m. In homologous series, the surfactants most prone to crystallizing are those with borderline solubility, which possess just enough oxyethylene groups to promote solubility in cold water. Large POE moieties depress or eliminate KPs.
Kurzfassung
Die Löslichkeit von polyoxyethylierten nichtionischen Tensiden (POSs) in Wasser ist durch eine obere und untere kritische Temperatur begrenzt. Die erstere, der sogenannte Trübungspunkt (CP), ist die Temperatur, bei der beim Erhitzen POSs aus der Lösung ausfallen, aufgrund überhöhter Dehydratisierung ihrer Polyoxyethylen (POE) Reste. Die letztere, der sogenannte Krafftpunkt (KP), ist die Temperatur, bei der beim Abkühlen POSs aus der Lösung auskristallisieren, aufgrund zunehmender Anordnung und Anziehungskräfte zwischen den Kohlenwasserstoffketten. Es tritt weniger häufig auf: Selbst wenn die POSs zur Kristallisation fähig sind, kristallisiert Eis oft zuerst.
Wässrige Lösungen von über 100 POSs wurden untersucht, indem ihre CPs bestimmt und ermittelt wurde, ob sie KPs aufweisen. KPs wurden bei polyoxyethylierten primären Alkoholen, Fettsäureamiden und Polyethylenglykolestern von Fettsäuren gefunden. Nur Tenside mit streng linearen Kohlenwasserstoffketten weisen KPs auf. Jede Verzweigung, einschließlich die in polyoxyethylierten linearen sekundären Alkoholen, verhindert die Kristallisation. Eine Kristallisation tritt nur dann auf, wenn die Anzahl m der Kohlenstoffatome in den Kohlenwasserstoffketten gleich oder größer als 12 ist. Die KPs sind dann proportional zu m. In homologen Reihen sind Tenside mit der größten Neigung zur Kristallisation diejenigen mit Grenzlöslichkeit, die gerade genug Oxyethylengruppen aufweisen um die Löslichkeit in kaltem Wasser zu begünstigen. Große POE-Reste erniedrigen oder unterbinden KPs.
References
1. Krafft, F. and Wiglow, H.: Chem. Ber.28 (1895) 2566.Suche in Google Scholar
2. Shinoda, K., Nakagawa, T., Tamamushi, B.-I. and Isemura, T.: Colloidal Surfactants, Academic Press, New York1963.Suche in Google Scholar
3. Rosen, M. J.: Surfactants and Interfacial Phenomena, 3rd edition, Wiley-Inter-science, New York2004.10.1002/9781118228920Suche in Google Scholar
4. Myers, D.: Surfactant Science & Technology, 2nd edition, VCH Publishers, New York1988, 83–84.10.1002/047174607XSuche in Google Scholar
5. Attwood, D.: J. Phys. Chem.72 (1968) 339.Suche in Google Scholar
6. Schott, H. and Han, S. K.: J. Pharm. Sci.65 (1976) 979.Suche in Google Scholar
7. Schick, M. J., editor: Nonionic Surfactants, Marcel Dekker, New York1967.Suche in Google Scholar
8. Murray, R. C. and Hartley, G. S.: Trans. Faraday Soc.31 (1935) 183.Suche in Google Scholar
9. Moroi, Y. and Matuura, R.: Bull. Chem. Soc. Jpn.61 (1988) 333.Suche in Google Scholar
10. Moroi, Y., Sugii, R. and Matuura, R.: J. Colloid Interface Sci.98 (1984) 184.Suche in Google Scholar
11. Shinoda, K. and Hutchinson, E.: J. Phys. Chem.66 (1962) 577.Suche in Google Scholar
12. Shinoda, K. and Soda, T.: J. Phys. Chem.67 (1963) 2072.Suche in Google Scholar
13. Schott, H.: J. Colloid Interface Sci.189 (1997) 117.Suche in Google Scholar
14. Imae, T., Sasaki, M., Abe, A. and Ikeda, S.: Langmuir4 (1988) 414.10.1021/la970390bSuche in Google Scholar
15. Schott, H.: J. Pharm. Sci.58 (1969) 1433.Suche in Google Scholar
16. van Os, N. M., Haak, J. R. and Rupert, L. A. M.: Physico-Chemical Properties of Selected Anionic Cationic and Nonionic Surfactants, Elsevier, Amsterdam1993.Suche in Google Scholar
17. Mitchell, D. J., Tiddy, G. J. T., Waring, L., Bostock, T. and McDonald, M. P.: J. Chem. Soc., Faraday Trans. I, 79 (1983) 975.10.1039/f19837900975Suche in Google Scholar
18. Nishikido, N.: J. Colloid Interface Sci.136 (1990) 401.Suche in Google Scholar
19. Strey, R., Schomaeker, R., Roux, D., Nallet, F. and Olsson, U.: J. Chem. Soc., Faraday Trans.86 (1990) 2253.Suche in Google Scholar
20. Schott, H.: Colloids Surfaces186 (2001) 129.Suche in Google Scholar
21. Zulauf, M., Weckstroem, K., Hayter, J. B., Degiorgio, V. and Corti, M.: J. Phys. Chem.89 (1985) 3411.Suche in Google Scholar
22. Balzer, D.: Langmuir9 (1993) 3375.Suche in Google Scholar
23. Cummins, P. G., Staples, E., Penfold, J. and Heenan, R. K.: Langmuir5 (1989) 1195.Suche in Google Scholar
24. Schott, H. and Han, S. K.: J. Pharm. Sci.64 (1975) 658.Suche in Google Scholar
25. Schick, M. J., editor: Nonionic Surfactants: Physical Chemistry, Marcel Dekker, New York1987.Suche in Google Scholar
26. Schott, H.: J. Colloid Interface Sci.24 (1967) 193.Suche in Google Scholar
27. Schott, H.: J. Pharm. Sci.84 (1995) 1215.Suche in Google Scholar
28. Schwartz, A. M.Perry, J. W., and Berch, J.: Surface Active Agents and Detergents, Interscience Publishers, New York1958, Vol. II, Chap. 2.Suche in Google Scholar
29. Hinds, G. E. in Anionic Surfactants (Linfield, W. M., editor), Marcel Dekker, New York1976, Part I, Chap. 2.Suche in Google Scholar
30. Schott, H.: J. Colloid Interface Sci.192 (1997) 458.Suche in Google Scholar
31. Schott, H.: J. Pharm. Sci.69 (1980) 369.Suche in Google Scholar
32. The U. S. Pharmacopeia 27th revision/The National Formulary 22nd edition, U. S. Pharmacopeial Convention, Rockville, MD 2004.Suche in Google Scholar
33. Schott, H.: J. Colloid Interface Sci.260 (2003) 219.Suche in Google Scholar
34. Mathis, G., Leempoel, P., Ravey, J.-C., Selve, C. and Delpuech, J.-J.: J. Am. Chem. Soc.106 (1984) 6162.Suche in Google Scholar
© 2005, Carl Hanser Publisher, Munich
Artikel in diesem Heft
- Contents/Inhalt
- Contents
- Abstracts
- Abstracts
- Review Article
- The Problem of Purity in Evaluating Surfactant Performance
- Environmental Chemistry
- Bleaching Product Development in View of Ecological Aspects
- Application
- Surfactant Enhanced Washing of Drilling Fluids, a Promising Remediation Technique
- Physical Chemistry
- Krafft Points and Cloud Points of Polyoxyethylated Nonionic Surfactants
- Reaction Kinetics of the Heterogenous Decomposition of Hydrogen Peroxide in Microemulsions
- Performance of some Surfactants as Wetting Agents
Artikel in diesem Heft
- Contents/Inhalt
- Contents
- Abstracts
- Abstracts
- Review Article
- The Problem of Purity in Evaluating Surfactant Performance
- Environmental Chemistry
- Bleaching Product Development in View of Ecological Aspects
- Application
- Surfactant Enhanced Washing of Drilling Fluids, a Promising Remediation Technique
- Physical Chemistry
- Krafft Points and Cloud Points of Polyoxyethylated Nonionic Surfactants
- Reaction Kinetics of the Heterogenous Decomposition of Hydrogen Peroxide in Microemulsions
- Performance of some Surfactants as Wetting Agents
