Ernst-Berl Institute of Technical and Macromolecular Chemistry , Technische Universität Darmstadt , Alarich-Weiss-Straße 4 , 64287 Darmstadt , Germany.
Chair in Polymer Chemistry , Universität des Saarlandes , Campus Saarbrücken , 66123 Saarbrücken , Germany.
ACS Appl Mater Interfaces. 2019 Nov 27;11(47):44764-44773. doi: 10.1021/acsami.9b17606. Epub 2019 Nov 13.
The formation of colloidal crystals and their use as photonic materials are of high interest for various technologies in the field of sensing applications, as templates, absorber materials, catalysts, and membranes. In this study, core-shell particles consisting of a cross-linked poly(methyl methacrylate) core featuring a (polyacrylonitrile--styrene) shell are synthesized by starved-feed emulsion polymerization. The resulting particles are investigated with respect to size and monodispersity, as well as the core-to-shell ratio, by means of dynamic light scattering and transmission electron microscopy. Optimized particle sizes are 218 nm for the cores and 276 nm for the core-shell particles. For the formation of highly ordered and free-standing opal films, the particles are processed by the melt-shear organization technique. The resulting films show angle-dependent reflection colors, while reflected colors can be tailored by the design of the core-shell particles. As a focus of this work, polyacrylonitrile as part of the copolymer particle shell is advantageously used both for particle opal film stabilization and for tailoring the reflection colors of the opal films. It is shown that the cyclization reactions at the interface of the particles and within the matrix material significantly influence the optical properties of the opal films upon thermal treatment at 240 °C and for different heat holding times. For instance, the change of color can be simply set from red to blue upon defined thermal treatment conditions. Via this convenient protocol, brilliant reflection colors can thus be obtained based on the insights into the structure-property relationships of the underlying particle architectures and interface reactions. The scalable opal films will pave the way to functional colored materials as interesting candidates for a manifold of sensing applications and temperature-responsive polymeric materials.
胶体晶体的形成及其作为光子材料在传感应用领域的各种技术中具有很高的应用价值，例如作为模板、吸收材料、催化剂和膜。在这项研究中，通过饥饿进料乳液聚合合成了由交联聚甲基丙烯酸甲酯核和（聚丙烯腈-苯乙烯）壳组成的核壳粒子。通过动态光散射和透射电子显微镜研究了所得粒子的粒径和单分散性以及核壳比。优化的粒子粒径为 218nm 的核和 276nm 的核壳粒子。为了形成高度有序和独立的蛋白石薄膜，通过熔体剪切组织技术处理这些粒子。所得薄膜表现出依赖于角度的反射颜色，而反射颜色可以通过核壳粒子的设计进行调整。作为这项工作的重点，作为共聚粒子壳一部分的聚丙烯腈既有利于粒子蛋白石膜的稳定，也有利于调整蛋白石膜的反射颜色。结果表明，在 240°C 下进行不同的保温时间的热处理时，粒子界面和基体材料内的环化反应会显著影响蛋白石膜的光学性能。例如，在定义的热处理条件下，颜色可以简单地从红色变为蓝色。通过这种方便的方案，可以根据对底层粒子结构和界面反应的关系的深入了解获得绚丽的反射颜色。可扩展的蛋白石薄膜将为功能彩色材料铺平道路，这些材料是多种传感应用和温度响应聚合物材料的有趣候选材料。
