Mixed Micelles of a PEO-PPO-PEO Triblock Copolymer (P123) and a Nonionic Surfactant (C12EO6) in Water. A Dynamic and Static Light Scattering Study
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- 作者：Karin Schillé ; n ; Jö ; rgen Jansson ; David Lö ; f ; Telma Costa
- 刊名：Journal of Physical Chemistry B
- 出版年：2008
- 出版时间：May 8, 2008
- 年：2008
- 卷：112
- 期：18
- 页码：5551 - 5562
- 全文大小：181K
- 年卷期：v.112,no.18(May 8, 2008)
- ISSN：1520-5207
文摘
The present article reports on static and dynamic light scattering (SLS and DLS) studies of aqueous solutionsof the nonionic surfactant C12EO6 and the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)triblock copolymer EO20PO68EO20 (P123) at temperatures between 25 and 45 
C. In water, P123 self-assemblesinto spherical micelles with a hydrodynamic radius of 10 nm, and at 40 C, these micelles consist of 131unimers. Addition of C12EO6 leads to an association of the surfactant molecules to the P123 micelles andmixed micelles are formed. The size and structure of the mixed micelles as well as interparticle interactionswere studied by varying the surfactant-to-copolymer (C12EO6/P123) molar ratio. The novelty of this studyconsists of a composition-induced structural change of the mixed micelles at constant temperature. Theygradually change from being spherical to polymer-like with increasing C12EO6 content. At low C12EO6/P123molar ratios (below 12), the SLS measurements showed that the molar mass of the mixed micelles decreaseswith an increasing amount of C12EO6 in the micelles for all investigated temperatures. In this regime, themixed micelles are spherical and the DLS measurements revealed a decrease in the hydrodynamic radius ofthe mixed micelles. An exception was found for C12EO6/P123 molar ratios between 2 and 3, where the mixedmicelles become rodlike at 40 C. This was the subject of a previous study1 and has hence not been investigatedhere. At high molar ratios (48 and above), the polymer-like micelles present a concentration-induced growth,similar to that observed in the pure C12EO6/water system.
C. In water, P123 self-assemblesinto spherical micelles with a hydrodynamic radius of 10 nm, and at 40 C, these micelles consist of 131unimers. Addition of C12EO6 leads to an association of the surfactant molecules to the P123 micelles andmixed micelles are formed. The size and structure of the mixed micelles as well as interparticle interactionswere studied by varying the surfactant-to-copolymer (C12EO6/P123) molar ratio. The novelty of this studyconsists of a composition-induced structural change of the mixed micelles at constant temperature. Theygradually change from being spherical to polymer-like with increasing C12EO6 content. At low C12EO6/P123molar ratios (below 12), the SLS measurements showed that the molar mass of the mixed micelles decreaseswith an increasing amount of C12EO6 in the micelles for all investigated temperatures. In this regime, themixed micelles are spherical and the DLS measurements revealed a decrease in the hydrodynamic radius ofthe mixed micelles. An exception was found for C12EO6/P123 molar ratios between 2 and 3, where the mixedmicelles become rodlike at 40 C. This was the subject of a previous study1 and has hence not been investigatedhere. At high molar ratios (48 and above), the polymer-like micelles present a concentration-induced growth,similar to that observed in the pure C12EO6/water system.