Photonic Crystals via 3D Printing of Block Co-polymers

光子晶体是周期性纳米结构材料，其反射特定波长的光，从而允许控制和操纵光。可以在自然界中找到的结构色包括例如蛋白石、孔雀和蝴蝶。人工光子晶体被用作光导或反射器，并具有实现高速光学计算的潜力。迄今为止，光子晶体的制造是昂贵的或在几何形状上受到限制。三维（3D）打印光子晶体材料的能力将能够通过经济和多功能的平台生产能够控制光流动的复杂物体，并将加速其在各种应用中的部署。该奖项支持通过3D打印组装到光子晶体的嵌段共聚物合成的基础研究。这项工作的更广泛影响将建立3D打印光子晶体的技术，并实现可持续结构颜色，太阳能收集和城市热岛缓解等应用。这项工作将通过在实验室和课堂环境中接触这些主题，在多个学科（包括工程、材料和聚合物科学以及3D打印）中教育下一代科学家。由于自下而上的自组装和使用商品塑料的潜力，嵌段共聚物组装到光子晶体在经济上是有吸引力的。然而，组装到具有足够大的畴尺寸以在可见光谱中产生光子带隙的纳米结构材料是具有挑战性的。在很大程度上，这一挑战源于聚合物链缠结的基本性质，它为自组装引入了能量障碍。研究团队将专注于设计嵌段共聚物，以降低这种能量障碍，并增强在3D打印时间尺度上组装的能力。通过这些研究获得的基础知识将应用于3D打印光学光导。

Photonic crystals are periodic nanostructured materials that reflect specific wavelengths of light allowing for control and manipulation of light. Structural colors that can be found in nature include opals, peacocks and butterflies, for example. Artificial photonic crystals are used as light guides or reflectors and possess the potential to enable high speed optical computing. To date, the fabrication of photonic crystals is expensive or limited in geometric shape. The ability to three dimensionally (3D) print photonic crystal materials will enable the production of complex objects capable of controlling the flow of light via an economical and versatile platform and will accelerate their deployment for a variety of applications. This award supports fundamental research in the synthesis of block copolymers that assemble to photonic crystals through 3D printing. The Broader Impacts of this work will establish the technology to 3D print photonic crystals and enable application such as sustainable structural color, solar energy harvesting, and urban heat island mitigation. This work will serve to educate next-generation scientists in STEM across several disciplines, including engineering, materials and polymer science, and 3D printing, through exposure to these topics in laboratory and classroom environments. The assembly of block copolymers to photonic crystals is economically attractive due to bottom-up self-assembly and the potential to use commodity plastics. However, the assembly to nanostructured materials with domain sizes large enough to give rise to photonic bandgaps in the visible spectrum is challenging. In large part, this challenge arises from the fundamental property of polymer chain entanglement, which introduces an energy barrier to self-assembly. The research team will focus on designing block copolymers that reduce this energy barrier and have enhanced capability for assembly on the timescale of 3D printing. The fundamental knowledge gained through these studies will be applied toward 3D printing optical light guides.