Charge‐Reversible Surfactant‐Induced Transformation Between Oil‐in‐Dispersion Emulsions and Pickering Emulsions.
Binks, Bernard P.
INTELLIGENT control systems
Angewandte Chemie; 5/17/2021, Vol. 133 Issue 21, p11899-11904, 6p
A novel charge‐reversible surfactant, (CH3)2N‐(CH2)10COONa, was designed and synthesized, which together with silica nanoparticles can stabilize a smart n‐octane‐in‐water emulsion responsive to pH. At high pH (9.3) the surfactant is anionic carboxylate, which together with the negatively charged silica nanoparticles co‐stabilize flowable oil‐in‐dispersion emulsions, whereas at low pH (4.1) it is turned to cationic form by forming amine salt which can hydrophobize in situ the negatively charged silica nanoparticles to stabilize viscous oil‐in‐water (O/W) Pickering emulsions. At neutral pH (7.5), however, this surfactant is converted to zwitterionic form, which only weakly hydrophobises the silica particles to stabilize O/W Pickering emulsions of large droplet size. Moreover, demulsification can be achieved rapidly triggered by pH. With this strategy particles can be controlled either dispersed in water or adsorbed at the oil‐water interface endowing emulsions with the capacity for intelligent and precise control of stability as well as viscosity and droplet size. [ABSTRACT FROM AUTHOR]
Copyright of Angewandte Chemie is the property of John Wiley & Sons, Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)