Key Laboratory of Carbon Fibers and Functional Polymers, Ministry of Education, Beijing 100029, PR China; Beijing Engineering Research Center for the Synthesis and Applications of Waterborne Polymers, Beijing 100029, PR China; College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, PR China.
Key Laboratory of Carbon Fibers and Functional Polymers, Ministry of Education, Beijing 100029, PR China; Beijing Engineering Research Center for the Synthesis and Applications of Waterborne Polymers, Beijing 100029, PR China; College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, PR China.
J Colloid Interface Sci. 2021 Jun 15;592:249-258. doi: 10.1016/j.jcis.2021.02.068. Epub 2021 Feb 21.
In this study, a facile method to fabricate Janus microbeads based on photonic crystals and upconversion nanoparticles is designed. The Janus microbeads can be reversed under magnetic response and generate upconversion fluorescence under near-infrared light. Three kinds of core-shell upconversion nanoparticles (UCNPs) are prepared by the solvothermal method and are mixed with FeO nanoparticles and different sizes of colloidal spheres. The Janus microbeads are assembled according to the hydrophilic property of the mixture and the hydrophobic property of substrates. The upper parts of the Janus microbeads are photonic crystals assembled with colloidal spheres, and the other parts are FeO. Meanwhile, UCNPs are distributed inside the Janus microbeads. Furthermore, the Janus microbeads are prepared into different lattice patterns using special templates. In the lattice patterns, the structural colors of Janus microbeads can be displayed and disappeared by magnetic field inversion, and under external NIR irradiation, Janus microbeads can generate upconversion fluorescence to achieve multiple color display. The Janus microbeads are also applied to both sides of the bank card, and various reading information methods are designed according to different response modes, which have important applications in pattern display, response materials, and anti-counterfeiting.
在这项研究中，设计了一种基于光子晶体和上转换纳米粒子制备各向异性微球的简便方法。各向异性微球可以在磁场响应下反转，并在近红外光下产生上转换荧光。通过溶剂热法制备了三种核壳型上转换纳米粒子（UCNP），并将其与 FeO 纳米粒子和不同尺寸的胶体球混合。根据混合物的亲水性和基底的疏水性，组装各向异性微球。各向异性微球的上部是由胶体球组装而成的光子晶体，其他部分是 FeO。同时，UCNP 分布在各向异性微球内部。此外，使用特殊模板将各向异性微球制备成不同的晶格图案。在晶格图案中，通过磁场反转可以显示和消失各向异性微球的结构颜色，并且在外部 NIR 照射下，各向异性微球可以产生上转换荧光，从而实现多种颜色显示。各向异性微球还应用于银行卡的两面，并根据不同的响应模式设计了各种读取信息的方法，在图案显示、响应材料和防伪等方面具有重要的应用。
