Ni Mingli, Luo Wen, Wang Dan, Zhang Yue, Peng Haiyan, Zhou Xingping, Xie Xiaolin
Key Lab for Material Chemistry of Energy Conversion and Storage, Ministry of Education, and Hubei Key Lab of Materials Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
National Anti-Counterfeit Engineering Research Center, Wuhan 430074, China.
ACS Appl Mater Interfaces. 2021 Apr 28;13(16):19159-19167. doi: 10.1021/acsami.1c02561. Epub 2021 Apr 20.
Crosstalk-free reconstruction of multiple images within a single element can greatly boost the image capacity and information security. We herein demonstrate a viable approach by integrating upconversion and holographic images into a single holographic polymer nanocomposite. The holographic image is reconstructed through photopolymerization-induced phase separation under a 460 nm laser and identifiable under room light, while the upconversion image recognizable under a 980 nm laser is photopatterned via spatially photobleaching of the dye embedded in the upconversion nanoparticle (UCNP) shell under 365 nm light. To this end, the lanthanide-doped UCNP in the core/shell/shell nanostructure of NaYF:20%Yb,0.5%Tm@NaYF@SiO is designed, and the dye, fluorescein isothiocyanate (FITC), is fixed in the outermost SiO shell via the amine-isothiocyanate reaction and the subsequent sol-gel reaction. Energy transfer from the core of the UCNP to FITC embedded in the shell is critical to boosting the contrast of the upconversion image, which dials the emission color from blue to yellow-green. It is also found that the upconversion image can be brightened by increasing the UCNP content while the holographic image is weakened when the UCNP content is over 15 wt %. This study paves a new way toward advanced anticounterfeiting.
在单个元件内无串扰地重建多个图像可极大地提高图像容量和信息安全性。我们在此展示了一种可行的方法，即将上转换图像和全息图像集成到一种全息聚合物纳米复合材料中。全息图像通过在460 nm激光下光聚合诱导相分离来重建，在室内光线下可识别，而上转换图像在980 nm激光下可识别，它是通过在365 nm光下对嵌入上转换纳米颗粒（UCNP）壳层中的染料进行空间光漂白来进行光图案化的。为此，设计了NaYF:20%Yb,0.5%Tm@NaYF@SiO核/壳/壳纳米结构中的镧系掺杂UCNP，染料异硫氰酸荧光素（FITC）通过胺-异硫氰酸酯反应和随后的溶胶-凝胶反应固定在最外层的SiO壳层中。UCNP核心到壳层中嵌入的FITC的能量转移对于提高上转换图像的对比度至关重要，这使得发射颜色从蓝色变为黄绿色。还发现，增加UCNP含量可使上转换图像变亮，而当UCNP含量超过15 wt%时全息图像会减弱。这项研究为先进的防伪技术开辟了一条新途径。
