High Dielectric Performances of Flexible and Transparent Cellulose Hybrid Films Controlled by Multidimensional Metal Nanostructures
High Dielectric Performances of Flexible and Transparent Cellulose Hybrid Films Controlled by Multidimensional Metal Nanostructures
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DOI：
10.1002/adma.201700538
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发表时间：
2017-06-27
影响因子：
29.4
通讯作者：
Park, Jang-Ung
中科院分区：
文献类型：
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作者：
Ji, Sangyoon;Jang, Jiuk;Park, Jang-Ung
已经针对广泛的户外活动开发了各种可穿戴电子设备。这些可穿戴设备的关键指标是柔性触摸屏面板（TSP）的高触摸灵敏度和良好的机械和热稳定性。它们的介电常数（k）对于高触摸灵敏度是重要的。因此，研究具有高k值的柔性和透明覆盖层具有突出的机械和热可靠性是必不可少的。本文报道了一种用于形成柔性和透明纤维素纤维（CNF）膜的非常规方法。这些薄膜用于嵌入超长金属纳米纤维，作为纳米填料，以显着增加k（9.2以上，90%的高透射率）。此外，通过控制这些填料的尺寸和长径比，研究了它们的纳米结构和含量对薄膜光学和介电性能的影响。纳米纤维的长度可以使用拉伸方法来控制，以破坏高度对齐的超长纳米纤维。这些纳米纤维嵌入的高k薄膜具有机械和热稳定性，并且它们具有比商业透明塑料更好的杨氏模量和拉伸强度以及更低的热膨胀。使用高k CNF薄膜的智能手机高灵敏度TSP的演示表明，这种薄膜在下一代便携式电子设备中具有巨大的潜力。
Various wearable electronic devices have been developed for extensive outdoor activities. The key metrics for these wearable devices are high touch sensitivity and good mechanical and thermal stability of the flexible touchscreen panels (TSPs). Their dielectric constants (k) are important for high touch sensitivities. Thus, studies on flexible and transparent cover layers that have high k with outstanding mechanical and thermal reliabilities are essential. Herein, an unconventional approach for forming flexible and transparent cellulose nanofiber (CNF) films is reported. These films are used to embed ultralong metal nanofibers that serve as nanofillers to increase k significantly (above 9.2 with high transmittance of 90%). Also, by controlling the dimensions and aspect ratios of these fillers, the effects of their nanostructures and contents on the optical and dielectric properties of the films have been studied. The length of the nanofibers can be controlled using a stretching method to break the highly aligned, ultralong nanofibers. These nanofiber-embedded, high-k films are mechanically and thermally stable, and they have better Young's modulus and tensile strength with lower thermal expansion than commercial transparent plastics. The demonstration of highly sensitive TSPs using high-k CNF film for smartphones suggests that this film has significant potential for next-generation, portable electronic devices.