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.
Soft Matter. 2019 Oct 14;15(38):7547-7556. doi: 10.1039/c9sm01467e. Epub 2019 Sep 4.
The interactions between particles and the role of their physical properties are not well understood for the electrostatic formation of liquid marbles. Here we focus initially on the impact of increasing particle diameter (notionally 20 to 140 μm) on the ease of particle extraction from an advancing bed of charged particles beneath an earthed, suspended water droplet. A larger particle diameter increased the ease of extraction, due to decreased interparticle cohesion, with increased potential applied to the particle bed. Whilst particle extraction is a crucial step in liquid marble formation, transport to the droplet and subsequent coating and stabilisation of the liquid is also significant. Further investigation highlighted that the smaller particle diameters afforded increased liquid stabilisation due to increased coverage and smaller interstitial spaces between particles on the liquid surface. Optimal conditions for controllable liquid marble formation using electrostatics was postulated as a trade-off between drop-bed separation distance, applied potential and kinetics of coating when studying impact of particle size. Furthermore, preliminary modelling, utilising weakest-link statistics and fracture mechanics, of the experimental data was undertaken to focus on development of the relationship between particle properties and extractability in the presence of electrostatics. This model represents a step towards predicting the suitability of particles for use in the electrostatic formation of liquid marbles prior to undertaking experimental work.
对于通过静电作用形成的液滴，人们对颗粒之间的相互作用及其物理特性的作用还没有很好的了解。在这里，我们首先关注的是增加颗粒直径（名义上为 20 至 140μm）对从带电荷的颗粒床中提取颗粒的难易程度的影响，该颗粒床位于接地悬浮水滴下方并处于前进状态。随着施加到颗粒床的电势增加，较大的粒径会由于颗粒间的内聚力降低而使提取变得更容易。虽然颗粒提取是液滴形成的关键步骤，但将其输送到液滴并随后对其进行涂层和稳定化也很重要。进一步的研究表明，由于颗粒在液面上的覆盖范围增加和颗粒之间的间隙变小，较小的颗粒直径可增加液体的稳定性。在研究颗粒尺寸的影响时，使用静电可控液滴形成的最佳条件被假定为滴床分离距离、施加的电势和涂层动力学之间的折衷。此外，还利用最薄弱环节统计和断裂力学对实验数据进行了初步建模，以关注在存在静电的情况下颗粒特性与可提取性之间关系的发展。该模型代表了在进行实验工作之前预测颗粒在静电形成液滴中的适用性的一个步骤。
