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Responsive aqueous foams stabilized by silica nanoparticles hydrophobized in situ with a conventional surfactant

Binks, Bernard P.; Cui, Zhenggang; Jiang, Jianzhong; Pei, Xiaomei; Zhu, Yue


Bernard P. Binks

Zhenggang Cui

Jianzhong Jiang

Xiaomei Pei

Yue Zhu


In the recent past, switchable surfactants and switchable/stimulus-responsive surface-active particles have been of great interest. Both can be transformed between surface-active and surface-inactive states via several triggers, making them recoverable and reusable afterward. However, the synthesis of these materials is complicated. In this paper we report a facile protocol to obtain responsive surface-active nanoparticles and their use in preparing responsive particle-stabilized foams. Hydrophilic silica nanoparticles are initially hydrophobized in situ with a trace amount of a conventional cationic surfactant in water, rendering them surface-active such that they stabilize aqueous foams. The latter can then be destabilized by adding equal moles of an anionic surfactant, and restabilized by adding another trace amount of the cationic surfactant followed by shaking. The stabilization–destabilization of the foams can be cycled many times at room temperature. The trigger is the stronger electrostatic interaction between the oppositely charged surfactants than that between the cationic surfactant and the negatively charged particles. The added anionic surfactant tends to form ion pairs with the cationic surfactant, leading to desorption of the latter from particle surfaces and dehydrophobization of the particles. Upon addition of another trace amount of cationic surfactant, the particles are rehydrophobized in situ and can then stabilize foams again. This principle makes it possible to obtain responsive surface-active particles using commercially available inorganic nanoparticles and conventional surfactants.


Binks, B. P., Cui, Z., Jiang, J., Pei, X., & Zhu, Y. (2015). Responsive aqueous foams stabilized by silica nanoparticles hydrophobized in situ with a conventional surfactant. Langmuir : the ACS journal of surfaces and colloids, 31(47), 12937-12943.

Acceptance Date Nov 4, 2015
Online Publication Date Nov 5, 2015
Publication Date 2015-12
Deposit Date Dec 2, 2015
Publicly Available Date Dec 2, 2015
Journal Langmuir
Print ISSN 0743-7463
Electronic ISSN 1520-5827
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
Volume 31
Issue 47
Pages 12937-12943
Keywords Aqueous foams; Switchable surfactants; Silica nanoparticles
Public URL
Publisher URL
Additional Information This document is the Accepted Manuscript version of a Published Work that appeared in final form in Langmuir, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see


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