Charging and discharging of single colloidal particles at oil/water interfaces.
The physical behavior of solid colloids trapped at a fluid-fluid interface remains in itself an open fundamental issue. Here, we show that the gradients of surface tension can induce particles to jet towards the oil/water interface with velocities as high as ≈ 60 mm/s when particle suspensions come in contact with the interface. We hypothesize that rubbing between the particles and oil lead to the spontaneous accumulation of negative charges on the hemisphere of those interfacial particles that contact the oil phase by means of triboelectrification. The charging process is highly dependent on the sliding distances, and gives rise to long-ranged repulsions that protect interfacial particles from coagulating at the interface by the presence of electrolyte. These triboelectric charges, however, are compensated within several hours, which affect the stability of interfacial particles. Importantly, by charging different kinds of colloidal particles using various spreading solvents and dispersion methods, we have demonstrated that charging and discharging of single colloidal particles at oil/water interfaces impacts a broad range of dynamical behavior.
1] Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, P. R. China 230026 [2].
Peng
P
Gao
1] Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong [2].
XiaoChen
X
Xing
Department of Modern Physics, University of Science and Technology of China, Hefei, P. R. China 230026.
Ye
Y
Li
Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
To
T
Ngai
1] Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, P. R. China 230026 [2] Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, P. R. China 230026 [3] CAS Key Laboratory of Soft Matter Chemistry, University of Science and Technology of China, Hefei, P. R. China 230026.
Fan
F
Jin