Novel oil-in-water emulsions stabilised by ionic surfactant and similarly charged nanoparticles at very low concentrations

Xu, Maodong; Jiang, Jianzhong; Pei, Xiaomei; Song, Binglei; Cui, Zhenggang; Binks, B P

Abstract

Novel oil-in-water (O/W) emulsions are prepared which are stabilised by a cationic surfactant in combination with similarly charged alumina nanoparticles at concentrations as low as 10-5 M and 10-4 wt.%, respectively. The surfactant molecules adsorb at the oil-water interface to reduce the interfacial tension and endow droplets with charge ensuring electrical repulsion between them, whereas the charged particles are dispersed in the aqueous films between droplets retaining thick lamellae, reducing water drainage and hindering flocculation and coalescence of droplets. This stabilization mechanism is universal as it occurs with different oils (alkanes, aromatic hydrocarbons and triglycerides) and in mixtures of anionic surfactant and negatively charged nanoparticles. Further, such emulsions can be switched between stable and unstable by addition of an equimolar amount of oppositely charged surfactant which forms ion pairs with the original surfactant destroying the repulsion between droplets.

Citation

Xu, M., Jiang, J., Pei, X., Song, B., Cui, Z., & Binks, B. P. (2018). Novel oil-in-water emulsions stabilised by ionic surfactant and similarly charged nanoparticles at very low concentrations. Angewandte Chemie, 57(26), 7738-7742. https://doi.org/10.1002/anie.201802266

• Journal Article Type: Article
• Acceptance Date: Apr 23, 2018
• Online Publication Date: May 28, 2018
• Publication Date: Jun 25, 2018
• Deposit Date: Sep 18, 2018
• Publicly Available Date: May 29, 2019
• Print ISSN: 1433-7851
• Electronic ISSN: 1521-3773
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 57
• Issue: 26
• Pages: 7738-7742
• DOI: https://doi.org/10.1002/anie.201802266
• Keywords: Alumina; Nanoparticles; Cetyltrimethyl ammonium bromide (CTAB); Electrical repulsion; Emulsions
• Public URL: https://hull-repository.worktribe.com/output/797143
• Publisher URL: https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.201802266