CAREER: Illuminating molecular-level effects in new plant-based nanocomposites for additive manufacturing by stereolithography

植物是非凡的生物。它们是高耸的、由阳光驱动的工厂，利用二氧化碳、水和土壤养分来创造生存所需的所有材料，包括工厂本身！虽然许多人造工厂是用混凝土建造的，但植物用一种叫做聚合物的长分子来制造支撑结构。这些结构使植物能够站起来，接触阳光，在器官之间移动水分和营养物质，保护自己和后代。其中一种聚合物被称为木质素，它的功能就像混凝土中的水泥；它是一种粘合剂，把所有东西粘合在一起。它的化学结构与人们日常生活中使用的许多塑料非常相似。因此，木质素可以用来制造新的塑料，包括用于3D打印的塑料。使用木质素来3D打印物体就像植物使用木质素来制造叶子、茎、根和种子一样。此外，由于植物是一种可再生资源，由植物制成的塑料也将是可再生的，这与目前由原油制成的不可再生塑料正好相反。最后，由于植物利用二氧化碳制造木质素，种植新的植物来制造新的塑料将减少大气中的二氧化碳含量，从而减轻其对气候变化的影响。这个项目的目标是学习如何控制从植物中提取的木质素的结构，并用它来创建3D打印的新材料。将探索新的化学方法来提取、修饰和利用木质素。首席研究员还将研究如何使用木质素和其他植物聚合物来减轻气候变化的影响，以及如何使用它们来帮助农村社区的人们获得与这些新的可再生材料相关的好工作。此外，该研究计划将通过丰富聚合物科学与可持续性交叉的本科教育，支持与可持续性相关的本科研究机会，并通过教师研究经验项目向K12学生传播前沿研究原则来增强。本职业规划的总体目标是：(1)开发由适当改性的纳米纤维素和木质素组成的3D可打印复合树脂，(2)将本研究作为一个平台，向学生介绍聚合物科学的基本原理，以及支撑可再生生物产品的社会正义和可持续性问题。(3)通过降低大气碳浓度，为全球减少人为气候变化的影响做出贡献。拟议的职业规划将促进对几个领域的知识和理解，包括绿色工程、合成化学和聚合物科学与工程。目的包括(1)建立在分离和升级过程中控制木质素中脂肪族碳氧化态的方法，(2)开发控制木质素结构和作为光聚合聚合物基质功能的技术，以及(3)确定混合改性木质素原料以制造新的立体光刻树脂的方法。这些活动探索了变革性的概念，包括为3D打印生产完全可再生的生物复合树脂。此外，该研究计划将通过(1)丰富聚合物科学与可持续性交叉的本科教育，(2)支持与可持续性和“缩减”相关的本科研究机会，以及(3)通过“教师研究经验”向K12学生传播前沿研究原则来增强。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARYPlants are remarkable organisms. They are towering, sunlight-driven factories that use carbon dioxide, water, and soil nutrients to create all the materials they need to survive, including the factory itself! While many human-made factories are constructed using concrete, plants use long molecules called polymers to create supporting structures. These structures allow a plant to stand up and reach out for sunlight, move water and nutrients between its organs, and protect itself and its offspring. One of these polymers is called lignin, and it functions like the cement in concrete; it is a sort of glue that holds everything together. It also has a chemical structure that is very similar to many of the plastics that people use in everyday life. Therefore, lignin could be used to make new plastics, including those used for 3D printing. Using lignin to 3D print objects would be like how plants use lignin to manufacture their leaves, stems, roots, and seeds. Also, since plants are a renewable resource, plastics made from them would also be renewable, which is the opposite of current non-renewable plastics that are made from crude oil. Finally, since plants use carbon dioxide to make lignin, growing new plants to make new plastics would reduce the amount of carbon dioxide in the atmosphere, which could lessen its effect on climate change. The goal of this project is to learn how to control the structure of lignin taken from plants and use it to create new materials for 3D printing. New chemistry methods to extract, modify, and use lignin will be explored. The principal investigator will also study how using lignin and other plant polymers could lessen the effects of climate change and how using them could help people in rural communities get good jobs related to these new renewable materials. In addition, the research plan will be augmented by enriching undergraduate education at the intersection of polymer science and sustainability, supporting undergraduate research opportunities related to sustainability, and disseminating cutting edge research principles to K12 students through Research Experiences for Teachers program.TECHNICAL SUMMARYThe overarching goals of this CAREER plan are to (1) develop 3D printable composite resins consisting of suitably modified nanocellulose and lignin, (2) use this research as a platform to introduce students to both fundamental principles of polymer science and issues of social justice and sustainability that underpin renewable bioproducts, and (3) contribute to global efforts to diminish the effects of anthropogenic climate change by reducing the concentration of atmospheric carbon. The proposed CAREER plan will advance knowledge and understanding in several fields, including green engineering, synthetic chemistry, and polymer science and engineering. The aims include (1) establishing approaches to control the oxidation state of aliphatic carbons in lignin during fractionation and upgrading, (2) developing techniques to control lignin structure and function as a photopolymerizable polymer matrix, and (3) identifying methods to blend modified lignin feedstocks to create new stereolithography resins. These activities explore transformative concepts, including producing entirely renewable biocomposite resins for 3D printing. In addition, the research plan will be augmented by (1) enriching undergraduate education at the intersection of polymer science and sustainability, (2) supporting undergraduate research opportunities related to sustainability and “Drawdown,” and (3) disseminating cutting edge research principles to K12 students through Research Experiences for Teachers.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.