Pradhan Susav, Whitby Catherine P, Williams Martin A K, Chen Jack L Y, Avci Ebubekir
School of Fundamental Sciences, Massey University, Palmerston North 4410, New Zealand; Department of Mechanical and Electrical Engineering, Massey University, Palmerston North 4410, New Zealand; The MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6140, New Zealand.
School of Fundamental Sciences, Massey University, Palmerston North 4410, New Zealand; The MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6140, New Zealand.
J Colloid Interface Sci. 2022 Sep;621:101-109. doi: 10.1016/j.jcis.2022.04.044. Epub 2022 Apr 12.
The size, shape and dynamics of assemblies of colloidal particles optically-trapped at an air-water interface can be tuned by controlling the optical potential, particle concentration, surface charge density and wettability of the particles and the surface tension of the solution.
The assembly dynamics of different colloidal particle types (silica, polystyrene and carboxyl coated polystyrene particles) at an air-water interface in an optical potential were systematically explored allowing the effect of surface charge on assembly dynamics to be investigated. Additionally, the pH of the solutions were varied in order to modulate surface charge in a controllable fashion. The effect of surface tension on these assemblies was also explored by reducing the surface tension of the supporting solution by mixing ethanol with water.
Silica, polystyrene and carboxyl coated polystyrene particles showed distinct assembly behaviours at the air-water interface that could be rationalised taking into account changes in surface charge (which in addition to being different between the particles could be modified systematically by changing the solution pH). Additionally, this is the first report showing that wettability of the colloidal particles and the surface tension of the solution are critical in determining the resulting assembly at the solution surface.
通过控制光势、粒子浓度、粒子的表面电荷密度、润湿性以及溶液的表面张力，可以调节在空气 - 水界面处光阱捕获的胶体粒子聚集体的大小、形状和动力学。
系统地研究了不同类型胶体粒子（二氧化硅、聚苯乙烯和羧基包覆的聚苯乙烯粒子）在光势作用下于空气 - 水界面处的聚集动力学，从而能够研究表面电荷对聚集动力学的影响。此外，改变溶液的pH值，以便以可控的方式调节表面电荷。还通过将乙醇与水混合来降低支撑溶液的表面张力，从而探究表面张力对这些聚集体的影响。
二氧化硅、聚苯乙烯和羧基包覆的聚苯乙烯粒子在空气 - 水界面处表现出不同的聚集行为，考虑到表面电荷的变化（除了粒子之间存在差异外，还可以通过改变溶液pH值进行系统调节），这些行为是可以合理解释的。此外，这是第一份表明胶体粒子的润湿性和溶液的表面张力对于确定溶液表面形成的聚集体至关重要的报告。
