Aqueous Phase Behavior of Tetraethylene Glycol Decanoyl Ester (C9COE4) and Ether (C10E4) Investigated by Nuclear Magnetic Resonance Spectroscopic Techniques

详细信息    查看全文

• 作者：Anne-Ga&euml ; lle Fournial ; Ying Zhu ; Valé ; rie Molinier ; Gaston Vermeersch ; Jean-Marie Aubry ; Nathalie Azaroual
• 刊名：Langmuir
• 出版年：2007
• 出版时间：November 6, 2007
• 年：2007
• 卷：23
• 期：23
• 页码：11443 - 11450
• 全文大小：212K
• 年卷期：v.23,no.23(November 6, 2007)
• ISSN：1520-5827

文摘

The binary phase diagram of tetraethylene glycol decanoyl ester (C₉COE₄) was investigated in the micellar regionby PGSE-NMR (pulse field gradient spin echo nuclear magnetic resonance) and in the lamellar liquid crystalline stateby ²H NMR. Its behavior was compared to the ether counterpart, tetraethylene glycol decanoyl ether (C₁₀E₄), whosephase diagram is well-described. The determination of the self-diffusion coefficient as a function of concentrationpermitted not only a determination of the critical micellar concentration (cmc) values but also the determination ofthe size and shape of micelles formed by both compounds. The evolution of the self-diffusion coefficients in thevicinity of the cloud point was also studied, showing no micellar growth with increasing temperature. ²H NMR analysesat the border of and within the liquid crystalline region gave an insight into the lamellar phase structure. We investigatedin detail the lamellar phase of both compounds by comparing the values of quadrupolar splittings () measured underthe same conditions. Lower values were found for the ester compared to the ether: since the ester probably bindsmore water than the ether, these lower values would indicate a lower order parameter in the liquid crystal phase.NMR techniques, either PGSE-NMR or ²H NMR, were confirmed as useful tools to characterize aqueous phasebehavior of surfactants, providing supplementary information to the classical techniques such as visual observations,polarized optical microscopy (POM), and surface tension measurements. They also provide a unique insight into themolecular organization in the different phases formed.