Asare-Asher Samuel, Connor Jason N, Sedev Rossen
Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095, Australia.
Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095, Australia.
J Colloid Interface Sci. 2015 Jul 1;449:341-6. doi: 10.1016/j.jcis.2015.01.067. Epub 2015 Feb 7.
Liquid marbles are liquid droplets covered densely with small particles. They exhibit hydrophobic properties even on hydrophilic surfaces and this behaviour is closely related to the Cassie wetting state and the phenomenon of superhydrophobicity. Typical liquid marbles are of millimetre size but their properties are analogous to smaller capsules and droplets of Pickering emulsions. We study water marbles covered with an uneven multilayer of polyethylene particles. Their elastic properties were assessed under quasi-static conditions. The liquid marbles are highly elastic and can sustain a reversible deformation of up to 30%. The spring constant is of the same order of magnitude as that for bare water droplets. Therefore the elasticity of the liquid marble is provided mainly by the liquid menisci between the particles. Upon further compression, the spring constant increases up to the point of breakage. This increase may be due to capillary attraction acting across the emerging cracks in the particle coating. The stress-strain curve for liquid marbles is similar to that obtained with liquid-filled microcapsules. A mechanical scaling description proposed for capsules is qualitatively applicable for liquid marbles. The exact mechanical role of the multilayer particle network remains elusive.
液滴弹是被小颗粒密集覆盖的液滴。它们即使在亲水性表面也表现出疏水特性，这种行为与卡西接触角状态和超疏水现象密切相关。典型的液滴弹尺寸为毫米级，但其特性类似于皮克林乳液中较小的胶囊和液滴。我们研究了覆盖有不均匀多层聚乙烯颗粒的水弹。在准静态条件下评估了它们的弹性特性。液滴弹具有高弹性，能够承受高达30%的可逆变形。其弹簧常数与裸水滴的弹簧常数处于同一数量级。因此，液滴弹的弹性主要由颗粒之间的液体弯月面提供。进一步压缩时，弹簧常数会增加直至破裂点。这种增加可能是由于毛细吸引力作用于颗粒涂层中出现的裂缝。液滴弹的应力-应变曲线与充液微胶囊的应力-应变曲线相似。为胶囊提出的机械标度描述定性地适用于液滴弹。多层颗粒网络的确切机械作用仍然难以捉摸。
