Nanoscale Control Over Interfacial Properties in Mixed Reverse Micelles Formulated by Using Sodium 1,4-bis-2-ethylhexylsulfosuccinate and Tri-n-octyl Phosphine Oxide Surfactants
The interfacial properties of pure reverse micelles (RMs) are a consequence of the magnitude and nature of noncovalent interactions between confined water and the surfactant polar head. Addition of a second surfactant to form mixed RMs is expected to influence these interactions and thus affect thes...
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Veröffentlicht in: | Chemphyschem 2016-08, Vol.17 (15), p.2407-2414 |
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Sprache: | eng |
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Zusammenfassung: | The interfacial properties of pure reverse micelles (RMs) are a consequence of the magnitude and nature of noncovalent interactions between confined water and the surfactant polar head. Addition of a second surfactant to form mixed RMs is expected to influence these interactions and thus affect these properties at the nanoscale level. Herein, pure and mixed RMs stabilized by sodium 1,4‐bis‐2‐ethylhexylsulfosuccinate and tri‐n‐octyl phosphine oxide (TOPO) surfactants in n‐heptane were formulated and studied by varying both the water content and the TOPO mole fraction. The microenvironment generated was sensed by following the solvatochromic behavior of the 1‐methyl‐8‐oxyquinolinium betaine probe and 31P NMR spectroscopy. The results reveal unique properties of mixed RMs and we give experimental evidence that free water can be detected in the polar core of the mixed RMs at very low water content. We anticipate that these findings will have an impact on the use of such media as nanoreactors for many types of chemical reactions, such as enzymatic reactions and nanoparticle synthesis.
Reverse micelles: At low water content, incorporation of tri‐n‐octyl phosphine oxide (TOPO) in sodium 1,4‐bis‐2‐ethylhexylsulfosuccinate (AOT) reverse micelles causes a progressive decrease in the mixed interfacial micropolarity, the hydrogen‐bond donor capability of water, and the “bulk‐like” water formation (see figure; QB=1‐methyl‐8‐oxyquinolinium betaine). |
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ISSN: | 1439-4235 1439-7641 |
DOI: | 10.1002/cphc.201600216 |