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Thermoresponsive Pickering emulsions stabilized by silica nanoparticles in combination with alkyl polyoxyethylene ether nonionic surfactant

Ling, Qi; Zhu, Yue; Fu, Ting; Liu, Kaihong; Lin, Qi; Pei, Xiaomei; Jiang, Jianzhong; Cui, Zhenggang; Binks, Bernard P.

Authors

Qi Ling

Yue Zhu

Ting Fu

Kaihong Liu

Qi Lin

Xiaomei Pei

Jianzhong Jiang

Zhenggang Cui

Abstract

We put forward a simple protocol to prepare thermo-responsive Pickering emulsions. Using hydrophilic silica nanoparticles in combination with a low concentration of alkyl polyoxyethylene monododecyl ether (C12En) nonionic surfactant as emulsifier, oil-in-water (o/w) emulsions can be obtained which are stable at room temperature but demulsified at elevated temperature. The stabilization can be restored once the separated mixture is cooled and re-homogenized, and this stabilization-destabilization behavior can be cycled many times. It is found that the adsorption of nonionic surfactant at the silica nanoparticle-water interface via hydrogen bonding between the oxygen atoms in the polyoxyethylene headgroup and the SiOH groups on particle surfaces at low temperature is responsible for the in situ hydrophobization of the particles rendering them surface-active. De-hydrophobization can be achieved at elevated temperature due to weakening or loss of this hydrogen bonding. The time required for demulsification decreases with increasing temperature and the temperature interval between stabilization and destabilization of the emulsions is affected by the surfactant headgroup length. Experimental evidence including microscopy, adsorption isotherms and three-phase contact angles is provided to support the mechanism.

Journal Article Type Article
Publication Date Jun 13, 2017
Journal Langmuir
Print ISSN 0743-7463
Electronic ISSN 1520-5827
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
Volume 33
Issue 23
Pages 5724-5733
Institution Citation Zhu, Y., Fu, T., Liu, K., Lin, Q., Pei, X., Jiang, J., …Binks, B. P. (2017). Thermoresponsive Pickering emulsions stabilized by silica nanoparticles in combination with alkyl polyoxyethylene ether nonionic surfactant. Langmuir : the ACS journal of surfaces and colloids, 33(23), 5724-5733. https://doi.org/10.1021/acs.langmuir.7b00273
DOI https://doi.org/10.1021/acs.langmuir.7b00273
Keywords Pickering emulsions; Nanoparticles; Nonionic surfactants
Publisher URL http://pubs.acs.org/doi/abs/10.1021/acs.langmuir.7b00273
Copyright Statement ©2018 University of Hull
Additional Information This is the accepted manuscript of an article published in Langmuir, 2017. The version of record is available at the DOI link in this record.

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