Influence of an Additive-Free Particle Spreading Method on Interactions between Charged Colloidal Particles at an Oil/Water Interface.
The assembly and manipulation of charged colloidal particles at oil/water interfaces represent active areas of fundamental and applied research. Previously, we have shown that colloidal particles can spontaneously generate unstable residual charges at the particle/oil interface when spreading solvent is used to disperse them at an oil/water interface. These residual charges in turn affect the long-ranged electrostatic repulsive forces and packing of particles at the interface. To further uncover the influence arising from the spreading solvents on interfacial particle interactions, in the present study we utilize pure buoyancy to drive the particles onto an oil/water interface and compare the differences between such a spontaneously adsorbed particle monolayer to the spread monolayer based on solvent spreading techniques. Our results show that the solvent-free method could also lead particles to spread well at the interface, but it does not result in violent sliding of particles along the interface. More importantly, this additive-free spreading method can avoid the formation of unstable residual charges at the particle/oil interface. These findings agree well with our previous hypothesis; namely, those unstable residual charges are triboelectric charges that arise from the violently rubbing of particles on oil at the interface. Therefore, if the spreading solvents could be avoided, then we would be able to get rid of the formation of residual charges at interfaces. This finding will provide insight for precisely controlling the interactions among colloidal particles trapped at fluid/fluid interfaces.
Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, Department of Polymer Science and Engineering, CAS Key Laboratory of Soft Matter Chemistry, University of Science and Technology of China , Hefei 230026, PR China.
Peng
P
Gao
Department of Chemistry, The Chinese University of Hong Kong , Shatin, N. T. Hong Kong.|Shenzhen Municipal Key Laboratory of Chemical Synthesis of Medicinal Organic Molecules, Shenzhen Research Institute, The Chinese University of Hong Kong , Shenzhen 518057, China.
Zonglin
Z
Yi
Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, Department of Polymer Science and Engineering, CAS Key Laboratory of Soft Matter Chemistry, University of Science and Technology of China , Hefei 230026, PR China.
Xiaochen
X
Xing
Department of Chemistry, The Chinese University of Hong Kong , Shatin, N. T. Hong Kong.|Shenzhen Municipal Key Laboratory of Chemical Synthesis of Medicinal Organic Molecules, Shenzhen Research Institute, The Chinese University of Hong Kong , Shenzhen 518057, China.
To
T
Ngai
Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, Department of Polymer Science and Engineering, CAS Key Laboratory of Soft Matter Chemistry, University of Science and Technology of China , Hefei 230026, PR China.
Fan
F
Jin