Rheological Behavior of Wormlike Micellar Solutions in Mixed Nonionic Systems of Polyoxyethylene Phytosterol-Polyoxyethylene Dodecyl Ether

概要

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Addition of lipophilic polyoxyethylene dodecyl ether (C12EOn) to the dilute micellar solution of polyoxyethylene phytosterol (PhyEOm m = 10 and 20) results in the increase in viscosity. The increase in viscosity is attributed to the C12EOn induced one-dimensional micellar growth leading to the formation of worm-like micelles. Steady and oscillatory shear rheological measurement in PhyEOm + C12EOn (n = 2-5) shows that on decreasing the EO chain length of C12EOn, in general, the one-dimensional micellar growth becomes increasingly favorable. However, with very short EO-chain, for example, C12EO2, phase separation occurs at a lower concentration before significant micellar growth can be induced. In the systems of C12EO3 and C12EO4, the wormlike micelles entangle to form a viscoelastic transient network having a dynamic rheology that can be described by Maxwellian model in wide range of shear frequency. It was found that increasing the concentration or decreasing the EO-chain length of PhyEOm in the mixed system favors one-dimensional micellar growth. Comparison of the rheological behavior of PhyEOm + C12EOn systems with that of polyoxyethylene cholesterol (ChEOm) + C12EOn systems at similar conditions shows that in the former system C12EOn can induce micellar growth more effectively, which is attributed to the additional branching of the alkyl chain in the lipophilic moiety of the amphiphile.
日本油化学会の論文
2004-12-01