Asaumi Yuta, Rey Marcel, Oyama Keigo, Vogel Nicolas, Hirai Tomoyasu, Nakamura Yoshinobu, Fujii Syuji
Division of Applied Chemistry, Graduate School of Engineering, Osaka Institute of Technology, 5-16-1 Omiya, Asahi-ku, Osaka 535-8585, Japan.
Institute of Particle Technology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstrasse 4, 91058 Erlangen, Germany.
Langmuir. 2020 Nov 10;36(44):13274-13284. doi: 10.1021/acs.langmuir.0c02265. Epub 2020 Oct 28.
A liquid marble (LM) describes a liquid droplet that is wrapped by nonwetting micro- or nanoparticles and therefore obtains characteristics of a solid powder particle. Here, we investigate the effect of the stabilizing particle size on the resulting structure and properties of the LM. We synthesize a series of polystyrene particles with ultrathin coatings of heptadecafluorooctanesulfonic acid-doped polypyrrole with diameters ranging between 1 and 1000 μm by an aqueous chemical oxidative seeded polymerization of pyrrole. The methodology produced a set of hydrophobic particles with similar surface characteristics to allow the formation of LMs and to probe size effects in the LM formation and stabilization efficiency. We found that particles with a size above 20 μm adsorb as a particle monolayer to the surface of the LM, while smaller particles are adsorbed as ill-defined, multilayered aggregates. These results indicate that the balance between particle-particle interaction and gravity is an important parameter to control the surface structure of the LMs. The assembly behavior and size of the particles also correlated with the mechanical integrity of the LM against fall impact. The mechanical resistance was affected by the gap distance between the inner liquid of the LM and supporting substrate, the capillary forces acting between the particles at the LM surface, and the potential energy that depended on the particle size. Last, we demonstrate that the broadband light-absorbing properties of the polypyrrole shell also allow manipulating the evaporation rate of the inner liquid.
液滴弹（LM）指的是被非润湿性微米或纳米颗粒包裹的液滴，因此具有固体粉末颗粒的特性。在此，我们研究了稳定颗粒尺寸对所得液滴弹结构和性质的影响。我们通过吡咯的水相化学氧化种子聚合反应，合成了一系列直径在1至1000μm之间、带有十七氟辛烷磺酸掺杂聚吡咯超薄涂层的聚苯乙烯颗粒。该方法制备了一组具有相似表面特性的疏水颗粒，以实现液滴弹的形成，并探究液滴弹形成过程中的尺寸效应和稳定效率。我们发现，尺寸大于20μm的颗粒以颗粒单层的形式吸附在液滴弹表面，而较小的颗粒则以不明确的多层聚集体形式吸附。这些结果表明，颗粒间相互作用与重力之间的平衡是控制液滴弹表面结构的一个重要参数。颗粒的组装行为和尺寸还与液滴弹抵抗坠落冲击的机械完整性相关。机械抗性受液滴弹内部液体与支撑基底之间的间隙距离、液滴弹表面颗粒间的毛细作用力以及取决于颗粒尺寸的势能影响。最后，我们证明了聚吡咯壳层的宽带光吸收特性还能调控内部液体的蒸发速率。
