快速磁、光响应变色体系的构建及其多重防伪机制

Stimuli-responsive photonic crystals have become a hotspot in the field of anti-counterfeiting materials due to their excellence in tunable colors and high concealment. The rapid responsive and multiple anti-counterfeiting are important frontiers for stimuli-responsive photonic crystals. In this project, a multiple anti-counterfeiting system with the rapid magnetically and optically responsive color-switching is developed, which takes advantages of the rapid color-switching characteristics of magnetically responsive photonic crystals and quantum dots under the stimuli of magnetic field and ultraviolet light, respectively. The project is based on the synthesis of superparamagnetic colloids with fluorescent properties which can be self-assembled into magnetically responsive photonic crystals. Moreover, the micro-droplets of these colloids are encapsulated by a polymer with high mechanical strength. Through the patterned design, combination and encoding, an effective anti-counterfeiting system with individual and synergistic response to magnetic field and ultraviolet light for color-switching is realized. The project focuses on the research of the relationship between the material’s composition and the color performance, the mechanism of the polymer encapsulation of colloids micro-droplets, and the anti-counterfeiting mechanism of the synergistic responses to magnetic field and ultraviolet light, providing data and theoretical basis for the anti-counterfeiting application of the material. This study will provide new insights into the construction of novel stimuli-responsive color-switching anti-counterfeiting materials.

刺激响应光子晶体因具有颜色可调、隐蔽性强等特点而成为防伪材料领域的研究热点，而快速响应与多重防伪是该类材料的重要前沿发展方向。本项目将磁响应光子晶体的快速磁响应变色与量子点的瞬时紫外光响应变色特性有机结合，创新构建快速磁、光响应变色多重防伪体系。项目以合成具有荧光特性、可组装成磁响应光子晶体的超顺磁荧光胶体粒子为基础，利用高机械强度聚合物对超顺磁荧光胶体粒子微液滴进行封装，并进行图案化设计、组合、编码，实现磁场、紫外光及二者协同响应变色的有效防伪。项目重点研究材料的结构组成与变色性能的关系、超顺磁荧光胶体粒子微液滴的封装机理及材料磁、光协同响应变色防伪机制，为材料快速响应变色防伪的应用提供理论依据，为新型刺激响应变色防伪材料的构建提供新思路。

假冒伪劣是严重威胁企业生存和消费者权益的全球性问题，开发新型防伪技术是解决假冒伪劣的有效途径。针对目前发光变色材料防伪技术因颜色变化单一和无法动态连续调变而导致防伪级别不高、易被仿制的问题，本项目将具有动态连续变色能力的力响应光子晶体和磁响应光子晶体分别与量子点荧光材料相结合，创制了具有动态连续响应变色性能的多重防伪材料与防伪体系，实现了高隐蔽、易识别、多功能的有效防伪。主要研究内容包括：1）通过静电组装法在SiO2微球表面负载CdTe QDs后进一步包覆一层SiO2制得SiO2@CdTe@SiO2 (SQS)荧光胶体粒子，并以此荧光胶体粒子构筑三维光子晶体阵列，再将其嵌入PDMS弹性体，成功制备了一种兼具力、光响应变色性能的PDMS/SQS/PDMS透明弹性薄膜。在施加拉力后，弹性薄膜立刻呈现明亮的结构色，且随着拉伸量的增加，弹性薄膜的衍射波长发生连续蓝移，移动范围可达115 nm。由于荧光胶体粒子中负载有CdTe QDs，弹性薄膜在紫外光的激发下可发射明亮荧光。通过图案化设计，利用弹性薄膜的力、光响应变色性能实现隐藏图案显现与动态连续变色，这在高级别防伪中具有重要应用潜力。2）结合Fe3O4@SiO2 (M)超顺磁胶体粒子动态连续的磁致变色和CdTe QDs瞬时发射的光致发光特性，采用PDMS弹性体封装含有M胶体粒子和CdTe QDs的乙二醇（EG）微液滴，成功制备了兼具磁、光响应变色性能的M/QDs/EG/PDMS复合薄膜。在外界磁场的诱导下，复合薄膜瞬时呈现明亮的结构色，且随着磁场强度的降低，复合薄膜的衍射波长发生连续红移，移动范围可达145 nm。在紫外光的激发下，复合薄膜还可呈现特定波长的荧光发射，具备良好的光致发光特性。通过图案化设计，成功制得了响应变色迅速、图案隐现可逆、颜色变化多样的防伪薄膜。本项目研究为刺激响应光子晶体与量子点的结合开辟了新的方向，同时也为发光变色防伪材料的研究提供了新的思路。