Magnetic cellulose microcrystals with tunable magneto-optical responses
Magnetic cellulose microcrystals with tunable magneto-optical responses
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DOI：
10.1016/j.apmt.2020.100749
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发表时间：
2020-09-01
影响因子：
8.3
通讯作者：
Yin, Yadong
中科院分区：
文献类型：
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作者：
Chen, Xin;Ye, Zuyang;Yin, Yadong
磁致液晶具有无电极操作、远程控制、成本低等优点，是传统液晶系统的潜在替代品。然而，它们的实际应用面临着一个重大挑战，即磁性元件的强烈光吸收，这些磁性元件大多是氧化铁基材料。在这里，我们通过开发一种由杆状纤维素微晶和磁性纳米颗粒附着在其表面的纳米复合材料来克服这一挑战。这种设计利用了纤维素微晶的光学透明度和双折射，以及它们的各向异性形状，当它们的表面被磁性纳米颗粒修饰时，允许它们有效地定向排列。只需要最少量的磁性纳米颗粒，就可以实现对纤维素微晶的即时和可逆定向控制，确保系统的高度透明度。通过结合磁对准和光刻工艺，这些独特的纳米复合材料可以固定在不同区域具有特定取向的聚合物基质中，从而产生在正常光照射下看起来接近透明的薄膜，并在夹在交叉偏振器之间时以高对比度显示图案。这项工作揭示了磁性组装策略的巨大潜力，使其成为防伪应用的一个有前途的候选者。(C)2020爱思唯尔有限公司。保留所有权利。
Magnetically actuated liquid crystals are potential alternatives to conventional liquid crystal systems in many applications thanks to their advantages of electrodeless operation, remote control, and low cost. However, their practical uses face a major challenge, namely the strong optical absorption of the magnetic components, which are mostly iron oxide-based materials. Here, we overcome this challenge by developing a nanocomposite composed of rod-shaped cellulose microcrystals with magnetite nanoparticles attached to their surfaces. This design takes advantage of the optical transparency and birefringence of the cellulose microcrystals, as well as their anisotropic shape which allows their efficient orientational alignment when their surfaces are modified by magnetite nanoparticles. Only a minimum amount of magnetite nanoparticles is required to enable instant and reversible orientational control of the cellulose microcrystals, ensuring a high degree of transparency of the system. These unique nanocomposites can be fixed in a polymer matrix with defined orientations at different regions by combining magnetic alignment and photolithography processes, producing thin films that appear near-transparent under the illumination of normal light and display patterns with high contrast when sandwiched between cross polarizers. This work reveals the enormous potential of the magnetic assembly strategy and making it a promising candidate for anti-counterfeiting applications. (c) 2020 Elsevier Ltd. All rights reserved.