Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia.
Division of Applied Chemistry, Graduate School of Engineering, Osaka Institute of Technology, 5-16-1 Omiya, Asahi-ku, Osaka 535-8585, Japan.
J Colloid Interface Sci. 2018 Nov 1;529:486-495. doi: 10.1016/j.jcis.2018.04.044. Epub 2018 Apr 10.
Particle cohesion and conductivity affects the electrostatically driven transport of particles to a suspended water droplet. The conditions at which liquid marbles and particle stabilised liquid droplets form are a function of these parameters.
Particle beds placed below an earthed pendent water drop had a negative potential applied, thus inducing an opposing positive charge on the liquid, which results in particle transfer and eventual coating of the liquid drop. Experiments where both the particle bed was constantly moved slowly toward the droplet, and the particle bed remained at a fixed, small separation distance were completed. These enabled the investigation of a number of variables that influence successful aggregate formation, including separation distance between the droplet and particle bed, coating mechanism and kinetics of the transfer process.
Monodisperse polystyrene core particles with polypyrrole shells of various cohesiveness and conductivity were observed to behave differently in the presence of the applied potential, where the least cohesive and conductive sample (polystyrene) required the smallest separation distance, i.e. the greatest field strength for particle transfer. Increasing conductivity of the particle shell decreases the field strength required for particle transfer, and thus an increase was observed in separation distance at which particles were observed to move to the air-water interface. The transfer kinetics followed the same trend where the least conductive and cohesive sample was the slowest to coat the air-water interface, and vice-versa. Since an increase in cohesion hinders particle transfer, it is concluded that particle conductivity is of greater importance in the electrostatic aggregation process.
颗粒的内聚性和导电性会影响颗粒在静电作用下向悬浮水滴的传输。形成液滴和颗粒稳定液滴的条件取决于这些参数。
将置于接地悬垂水滴下方的颗粒床施加负电势，从而使液体产生相反的正电荷，这导致颗粒转移并最终覆盖液滴。完成了缓慢地将颗粒床不断向液滴移动和颗粒床保持在固定的小分离距离的实验。这些实验使我们能够研究影响成功聚集形成的许多变量，包括液滴和颗粒床之间的分离距离、涂层机制和转移过程的动力学。
在施加的电势下，具有不同内聚性和导电性的单分散聚苯乙烯核颗粒表现出不同的行为，其中最不具内聚性和导电性的样品（聚苯乙烯）需要最小的分离距离，即用于颗粒转移的最大电场强度。颗粒壳的导电性增加会降低颗粒转移所需的电场强度，因此观察到颗粒移动到气-水界面的分离距离增加。转移动力学也遵循相同的趋势，其中最不导电和内聚性的样品是最慢覆盖气-水界面的，反之亦然。由于内聚性的增加会阻碍颗粒转移，因此可以得出结论，在静电聚集过程中，颗粒的导电性更为重要。
