上转换荧光光子晶体薄膜的制备及包装防伪应用

以热分解法制备的蓝色荧光NaYF4:Yb3+,Tm3+上转换纳米颗粒为核,外延生长一层具有钝化表面缺陷、增强荧光效果的NaYF4壳层,制备得到核壳上转换纳米颗粒(CSNPs).利用反相微乳液法在CSNPs上包覆一层修饰3-(三甲氧基甲硅基)甲基丙烯酸丙酯(MPS)的SiO2,实现上转换纳米颗粒亲水改性的同时,赋予其可参与加成聚合的双键.将CSNPs@SiO2-MPS与苯乙烯单体通过乳液聚合共聚形成镧系掺杂NaYF4/PS复合微球.通过垂直沉积法,利用镧系掺杂NaYF4/PS复合微球自组装构建上转换荧光光子晶体(UCPC)薄膜,并探讨其在包装防伪中的应用.结果表明:该上转换荧光光子晶体薄膜,在可见光下从特定角度可以观察到明显的粉色结构色,在980 nm激光照射下可观察到蓝色荧光,这两种模态下的光学特性可隐藏信息,预期在信息保护、包装防伪等领域有广阔的应用前景.

Synthesis of Upconversion Fluorescence Photonic Crystal Film for Packaging Anti-Counterfeiting Application

The NaYF4:Yb3+,Tm3+ upconversion nanoparticles (UCNPs) with blue fluorescence emission were prepared by thermal decomposition method. Then, the core-shell nanoparticles (CSNPs) with enhanced upconversion fluorescence were obtained by epitaxially growing a NaYF4 shell on UCNPs core. In order to realize hydrophilic modification of CSNPs and endow them with pendent polymerizable double bonds, a layer of SiO2 modified with 3-(Trimethoxysilyl) propyl methacrylate (MPS) were coated on CSNPs by reverse microemulsion method. Finally, lanthanide-doped NaYF4/PS composite microspheres were prepared via the emulsion polymerization of styrene in the presence of CSNPs@SiO2-MPS. The upconversion fluorescence photonic crystal (UCPC) film was constructed via the self-assemble of lanthanide-doped NaYF4/PS microspheres through the vertical deposition method. The result showed that the UCPC film could be observed not only in obvious pink structural color at specific angle of daylight, but also the blue fluorescence under 980 nm laser irradiation. The UCPC films with dual-mode optical characteristic could be used to in information encryption, which have broad application prospects in the fields of information protection and packaging anti-counterfeiting.