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Charge Density Overcomes Steric Hindrance of Ferrocene Surfactant in Switchable Oil-in-Dispersion Emulsions |
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| Authors: | Yunshan Liu Haojie Zhang Wanqing Zhang Prof Bernard P Binks Prof Zhenggang Cui Prof Jianzhong Jiang |
| Institution: | 1. The Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical & Material Engineering, Jiangnan University, 1800 Lihu Road, Wuxi, 214122 China
These authors contributed equally to this work.;2. Department of Chemistry, University of Hull, Hull, HU6 7RX UK;3. The Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical & Material Engineering, Jiangnan University, 1800 Lihu Road, Wuxi, 214122 China |
| Abstract: | A ferrocene surfactant can be switched between single and double head form (FcN+C12/Fc+N+C12) triggered by redox reaction. FcN+C12 can neither stabilize an O/W emulsion alone nor an oil-in-dispersion emulsion in combination with alumina nanoparticles due to the steric hindrance of the ferrocene group. However, such steric hindrance can be overcome by increasing the charge density in Fc+N+C12, so that oil-in-dispersion emulsions can be co-stabilized by Fc+N+C12 and alumina nanoparticles at very low concentrations (1×10−7 M (≈50 ppb) and 0.001 wt %, respectively). Not only can reversible formation/destabilization of oil-in-dispersion emulsions be achieved by redox reaction, but also reversible transformation between oil-in-dispersion emulsions and Pickering emulsions can be obtained through reversing the charge of alumina particles by adjusting the pH. The results provide a new protocol for the design of surfactants for stabilization of smart oil-in-dispersion emulsions. |
| Keywords: | Alumina Nanoparticles Charge Density Emulsion Ferrocene Surfactant Steric Hindrance |