Photochemically Induced, Polymer-Assisted Deposition for 3D Printing of Micrometer-Wide and Nanometer-Thin Silver Structures

该奖项支持将贡献与金属(银)结构的添加制造(AM)相关的新知识的研究，促进新制造技术的进步和推进广泛的科学应用。AM是从数字计算机模型制作几乎任何形状的三维对象的过程。这项技术通常被称为3D打印，它有可能彻底改变制造物品的方式。目前，制造金属零件的添加剂制造工艺有很多。然而，目前可用的几乎所有添加剂制造工艺都需要高温工艺，这往往会导致待印刷产品的损坏和产品性能的恶化。此外，由于金属粉末的尺寸限制，其中许多工艺仅限于尺寸为毫米级或更高的宏尺度部件。该奖项支持基础研究，以帮助开发能够实现高分辨率打印而不会热损坏的室温AM工艺。新工艺将利用基于溶液的逐层沉积，直接从可溶的金属盐中制备高反射和高导电的金属微结构。该工艺制造的金属微结构在半导体电子、能源、医疗保健、生物医学、航空航天、软机器人、汽车等行业有着广泛的应用。因此，这项研究的结果将有利于美国的经济和社会。这项研究涉及多个学科，包括制造、光化学、光子学和材料科学。这种多学科的方法将有助于扩大未被充分代表的群体参与研究和积极影响工程教育。目前AM金属制造主要依靠热或激光辅助金属熔化或金属粉末和纳米颗粒的喷墨打印，具有严重的局限性，包括特征尺寸大，表面粗糙，高光学/电子损失，以及与软材料不兼容。这项研究将通过探索一种新的基于溶液的光化学诱导聚合物辅助沉积工艺来填补这一知识空白，从而实现金属微结构的可扩展生产。研究小组将引入一种三维分子前体，由聚合物、金属盐和还原剂组成的相互交织的网络组成，在紫外线照射下可以形成连续的金属薄膜和结构。研究小组将建立一个模型来研究生长机制的基本化学和物理方面，设计一系列实验来验证模型，探索印刷结构的关键尺寸的基本极限，将理论和实验研究结合起来，并表征印刷薄膜的结构、光学和电学性能。此外，我们将把这项技术应用于各种衬底材料，包括非平坦表面，以构建三维结构。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This award supports research that will contribute new knowledge related to additive manufacturing (AM) of metallic (silver) structures, promoting both the progress of new manufacturing technologies and advancing a broad range of scientific applications. AM is the process of making a three-dimensional object of virtually any shape from a digital computer model. The technique, often called 3D printing, has the potential to revolutionize the way things are made. Currently, there are many additive manufacturing processes to make metal parts. However, almost all additive manufacturing processes currently available require high-temperature processes, which can often cause damage to the products to be printed and deteriorate the product performance. Additionally, many of these processes are limited to macroscale components, with dimensions at the millimeter scale or above, due to size limitations for metal powder. This award supports fundamental research to help develop a room-temperature AM process that enables high-resolution printing without thermal damage. The new process will utilize solution-based layer-by-layer deposition to produce highly reflective and highly conductive metal microstructures directly from soluble metal salts. The metallic microstructures produced by this process have wide applications in semiconductor electronics, energy, healthcare, biomedical, aerospace, soft robotics, and automotive industries. Therefore, results from this research will benefit the U.S. economy and society. This research involves several disciplines including manufacturing, photochemistry, photonics, and materials science. The multi-disciplinary approach will help broaden participation of underrepresented groups in research and positively impact engineering education.Prevalent AM metal manufacturing mainly relies on thermal or laser assisted metal fusion or ink-jet printing of metal powders and nanoparticles, and has serious limitations, including large feature sizes, rough surfaces, high optical/electrical loss, and incompatibility with soft materials. This research will fill this knowledge gap by exploring a new solution-based photochemically-induced polymer-assisted deposition process to allow scalable production of metal microstructures. The research team will introduce a three-dimensional molecular precursor, consisting of an interlaid network of polymers, metal salt, and reductants, that can turn into continuous metal films and structures upon ultraviolet illumination. The research team will build a model to study the fundamental chemical and physical aspects of the growth mechanism, design a series of experiments to verify the model, explore the fundamental limits of the critical dimensions of the printed structures, combine theoretical and experimental studies, and characterize the structural, optical, and electrical performance of the printed films. Further, we will apply this technique to a variety of substrate materials, including non-flat surfaces, to construct three-dimensional structures.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.