Ai Yuwen, Yangnan Jiang, He Jialei, Ohtsuka Yumiko, Sakai Miki, Seki Takahiro, Yamanaka Takahiro, Tarutani Naoki, Katagiri Kiyofumi, Takeoka Yukikazu
Department of Molecular & Macromolecular Chemistry, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
Graduate School of Advanced Science and Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan.
Langmuir. 2024 Sep 12. doi: 10.1021/acs.langmuir.4c02283.
In this study, photonic balls─spherical aggregates of submicrometer-sized silica particles with uniform particle size─were investigated as structural colored materials. The structural color of these photonic balls is influenced by the ordered arrangement of the silica particles. The research focused on how the addition of electrolytes, specifically NaCl, affects the formation of photonic balls to achieve the desired structural color. Without NaCl, the photonic balls formed onion-shaped colloidal crystals. At NaCl concentrations above 0.006 mol/L, the particles aggregated into short-range ordered structures. When the concentration exceeded 0.05 mol/L, the aggregates lost their spherical shape. The study also explored the addition of carbon black (CB), a water-dispersible material due to its surface charge. The findings revealed that NaCl induced the phase separation between the charged silica particles and CB, resulting in Janus-shaped photonic balls─one side exhibiting structural color and the other side appearing black due to the presence of CB. Changing the silica particle size altered the hues of these Janus-shaped photonic balls, though they appeared uniformly colored to the naked eye. While this study did not specifically examine the applications of Janus-shaped photonic balls composed of silica particles and CB, CB is known for its ability to absorb near-infrared radiation and convert it into heat as well as its conductive properties. Silica, on the other hand, has a low thermal conductivity and acts as an electrical insulator. The structurally colored Janus-shaped photonic balls created in this study may serve as pigments in applications requiring anisotropic heat generation and electrical conduction. Additionally, the study's findings suggest the potential for creating various types of Janus-shaped photonic balls from materials with differing densities.
在本研究中，光子球（即粒径均匀的亚微米级二氧化硅颗粒的球形聚集体）作为结构色材料进行了研究。这些光子球的结构色受二氧化硅颗粒有序排列的影响。该研究聚焦于添加电解质（特别是氯化钠）如何影响光子球的形成以实现所需的结构色。在没有氯化钠的情况下，光子球形成洋葱状胶体晶体。当氯化钠浓度高于0.006 mol/L时，颗粒聚集成短程有序结构。当浓度超过0.05 mol/L时，聚集体失去球形。该研究还探索了添加炭黑（CB），炭黑因其表面电荷而具有水分散性。研究结果表明，氯化钠诱导了带电二氧化硅颗粒与炭黑之间的相分离，从而产生了两面神形状的光子球，一面呈现结构色，另一面由于炭黑的存在而呈黑色。改变二氧化硅颗粒大小会改变这些两面神形状光子球的色调，尽管肉眼看起来它们颜色均匀。虽然本研究没有具体研究由二氧化硅颗粒和炭黑组成的两面神形状光子球的应用，但炭黑以其吸收近红外辐射并将其转化为热的能力以及导电性能而闻名。另一方面，二氧化硅具有低导热性且是电绝缘体。本研究中创建的具有结构色的两面神形状光子球可在需要各向异性发热和导电的应用中用作颜料。此外，该研究结果表明，利用不同密度的材料制造各种类型的两面神形状光子球具有潜力。
