Polyoxyethylene phytosterol

Naito, N., Acharya, D.P., Tanimura,)., and Kunieda, H. (2004) Rheological behavior of wormlike micellar solutions in mixed nonionic systems of polyoxyethylene phytosterol-polyoxyethylene dodecyl ether. J. Oleo Sci., 53, 599-606. 

Kunieda s group reported numerous viscoelastic worm-like micellar systems in the salt-free condition when a lipophilic nonionic surfactant such as short hydrophilic chain poly(oxyethylene) alkyl ether, C EOni, or N-hydroxyethyl-N-methylaUcanolamide, NMEA-n, was added to the dilute micellar solution of hydrophilic cationic (dodecyltrimethylammonium bromide, DTAB and hexade-cyltrimethylammonium bromide, CTAB) [12-14], anionic (sodium dodecyl sulfate, SDS [15, 16], sodium dodecyl trioxyethylene sulfate, SDES [17], and Gemini-type [18]) or nonionic (sucrose alkanoates, C SE [9, 19], polyoxyethylene cholesteryl ethers, ChEO [10, 20], polyoxyethylene phytosterol, PhyEO [11, 21] and polyoxyethylene sorbitan monooleate, Tween-80 [22]) surfactants. The mechanism of formation of these worm-Hke stmctures and the resulting rheological behavior of micellar solutions is discussed in this section based in some actual published and unpublished results, but conclusions can qualitatively be extended to aU the systems studied by Kunieda s group. 

FIG. 2 Critical micelle concentration (CMQ of polyoxyethylene derivatives of (-0-) cholesterols (from [11,13]), ( ) lanolin alcohols [10], (x) phytosterol [16], ( ) cholesteryl carbonate [24], and (A) octylphenol [21]. Increasing the length of the polyoxyethylene chain causes a decrease in the CMC for the sterol derivatives, initially causes a decrease in the CMC (minimum at 15 oxyethylene imits) for the lanolin alcohols and then an increase, while for the octylphenol derivatives the CMC increases with increasing hydrophilicity. 

The phase behavior of mixtures of polyoxyethylene phytosterol surfactants and paraiSn as well as ternary mixtures of the surfactants, water, and paraiSn has also been studied [18]. The objective of this work was to find creamy mixtures to be used in topical preparations. Uchegbu et al. investigated the phase behavior of cholesterol with 24 oxyethylene units with free cholesterol and hexadecyldiglycerol in order to find phases that can be used as drug delivery systems [25]. No liquid crystalline phases were found. 

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