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Partic. vol. 41 pp. 112-117 (December 2018)
doi: 10.1016/j.partic.2017.12.006

Synthesis of amphiphilic fluorinated Janus particles with applications in stabilizing surfactant-free foams

Gang Wanga,*, Keliang Wanga, Ying Wangb

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g.wang@stu.nepu.edu.cn

Highlights

    • Silica-based amphiphilic Janus particles (JPs) modified with fluorinated chains were synthesized. • Effect of JP concentration on their adsorption characteristics at air–water interface was studied. • The JPs could stabilize aqueous foams against coalescence and drainage without using surfactants.

Abstract

We report the preparation of amphiphilic Janus particles covered with fluorinated chains as well as the self-assembly and foam stabilization property of these particles over a limited range of concentrations. The structure and properties of these particles were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, fluorescence microscopy, pendant drop tensiometer, and foamscan. At a particle concentration of 0.6 wt%, the adsorption of the Janus particles at the interface was saturated and an equilibrium surface tension of approximately 35 mN/m was obtained. No further decreases in surface tension were observed with additional increases in the particle concentration. At a concentration of 0.4 wt%, the Gibbs stability criterion was achieved and the foam volume was almost constant throughout the observation period. Additionally, the liquid fraction of the foam exhibited a static equilibrium at each concentration assessed, demonstrating that drainage was arrested effectively. These results confirm that the use of amphiphilic Janus particles is an efficient approach to stabilizing foams.

Graphical abstract

Keywords

Janus particle; Fluorinated grafting agent; Amphiphilic particle; Self-assembly; Dynamic surface tension; Foam stability