Influence of Molecular Structure on the Size, Shape, and Nanostructure of Nonionic CnEm Surfactant Micelles

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• 作者：Faheem N. Padia ; Mohammed Yaseen ; Barbara Gore ; Sarah Rogers ; Gordon Bell ; Jian R. Lu
• 刊名：Journal of Physical Chemistry B
• 出版年：2014
• 出版时间：January 9, 2014
• 年：2014
• 卷：118
• 期：1
• 页码：179-188
• 全文大小：414K
• ISSN：1520-5207

文摘

Nonionic alkyl ethoxylates (C<sub>nsub>E<sub>msub>) have been extensively studied for their adsorption, aggregation, and solubilization individually and in small groups. In this work, we report a more systematic study of the effects of alkyl chain (tail) and ethoxylate (head) length on the size, shape, and extent of intermixing within the C<sub>nsub>E<sub>msub> micelles in aqueous solution. Data from small angle neutron scattering (SANS) and nuclear magnetic resonance (NMR) were combined to undertake the structural characterization of micelles formed from the two separate series of surfactants C<sub>nsub>E<sub>6sub> (n = 10, 12, 14) and C<sub>12sub>E<sub>msub> (m = 5, 6, 8, 10, 12). The micellar core volume (V<sub>coresub>) could be well determined with reasonable accuracy and linked to the hydrophilic鈥搇ipophilic balance (HLB) of the surfactant, with a sharp size and shape transition occurring around HLB = 12.5. NOESY NMR results revealed protrusions of the terminal methylene groups into the ethoxylate shell, thus providing direct experimental evidence for the phenomenon of 鈥渞oughness鈥?or intermixing of the core鈥搒hell interface. These detailed studies are compared with previous investigations on this model surfactant system.