SEES Fellows: Understanding the hierarchical assembly and economics of cellulose to enable high-performance, biomimetic, and sustainable composite materials

非技术性：该项目由材料研究部和化学部支持，在NSF科学，工程和可持续发展教育研究员（SEES研究员）计划的主持下进行，其目标是帮助实现所需的发现，为导致环境，能源和社会可持续性的行动提供信息，同时创造必要的劳动力来应对这些挑战。可持续发展科学是一个新兴的领域，它解决了在不损害环境的情况下满足人类需求的挑战，并且不牺牲后代满足其需求的能力。一个强大的科学队伍需要在跨学科研究和思维方面受过教育和培训的个人，特别是在可持续发展科学领域。在SEES奖学金的支持下，该项目将使一个有前途的早期职业研究人员能够在与可持续发展相关的独立研究生涯中确立自己的地位。该项目涉及复合材料的使用，这些材料在其高比强度和刚度超过其生产成本的应用中越来越普遍。在要求苛刻的应用中使用可持续材料展示了增材系统如何在经济和环境方面增强制造工艺。与麻省理工学院机械工程系的John哈特教授和布鲁克海文国家实验室功能纳米材料中心的Eric Stach教授合作，这位SEES研究员研究了纤维素来源和处理的组合变化和原位表征方法，以识别和理解全纤维素复合材料的结构变化。SEES研究员的重大专业发展将来自于在新学科中获得经验，学习新的实验和计算技术，以及开发可持续3D打印和CAD课程，以使更多人参与增材技术支持的产品设计机会，并教育公众制造业的环境方面。这将有助于现有的麻省理工学院教育计划的K-12学生，当地社区，并通过大规模开放的在线课程，更广泛的世界。技术：该项目解决了使纤维素复合材料具有竞争力所需的跨学科因素，从而促进了可持续材料在制造业中的使用。纤维素复合材料的物理性能受到缺乏对结构和界面结合如何转化为机械行为的理解的限制。该项目研究纤维素复合材料的仿生结构如何通过3D打印过程局部控制纤维排列，孔隙率和成分来增强机械性能。计算建模用于理解和预测最佳材料结构。此外，该项目还探讨了纤维素键合的可逆性是否可以实现一种可持续的可编程物质。为了使这些新型复合材料有助于全球可持续发展，它们需要被工业采用并带来环境效益。与卡内基梅隆大学工程与公共政策系的埃里卡富克斯教授合作，模拟建模和经验数据将用于比较增材制造的仿生纤维素复合材料与玻璃纤维复合材料的竞争地位和环境影响，并将假肢作为案例研究。将现有工艺的数据与使新材料具有竞争力所需的假设进行比较，将阐明该技术必须如何发展才能变得可行，以及它将产生最大经济和环境影响的应用。该项目的科学重点是了解结构-性能关系，并随后制定合理的策略，以提高纤维素复合材料的机械性能，这也将适用于其他生物材料和复合材料，如胶原蛋白或甲壳素。通过使用3D打印在多个长度尺度上编程材料特性来适应生物材料设计原则的能力也可能为复合材料的设计开辟一条新的途径。这项工作还将进一步了解如何利用成本建模指导技术开发走向可行的应用。

Non-technical:The project, supported by the Division of Materials Research and the Division of Chemistry, is made under the auspices of the NSF Science, Engineering and Education for Sustainability Fellows (SEES Fellows) program, with the goal of helping to enable discoveries needed to inform actions that lead to environmental, energy and societal sustainability while creating the necessary workforce to address these challenges. Sustainability science is an emerging field that addresses the challenges of meeting human needs without harm to the environment, and without sacrificing the ability of future generations to meet their needs. A strong scientific workforce requires individuals educated and trained in interdisciplinary research and thinking, especially in the area of sustainability science. With the SEES Fellowship support, this project will enable a promising early career researcher to establish himself in an independent research career related to sustainability. This project addresses the use of composite materials that are increasingly prevalent in applications where their high specific strength and stiffness outweigh the cost of their production. The use of sustainable materials in demanding applications demonstrate how additive systems enhance manufacturing processes both economically and environmentally. Working with Prof. John Hart of the Department of Mechanical Engineering at MIT and Prof. Eric Stach of the Center for Functional Nanomaterials at Brookhaven National Lab, this SEES Fellow investigates methods for combinatorial variation and in-situ characterization of cellulose source and treatments to discern and understand structural variation in all-cellulose composites. Significant professional development for the SEES Fellow will result from gaining experience in a new discipline, learning new experimental and computational techniques, as well as development of courses in sustainable 3D printing and CAD to enable wider participation in the opportunities for product design enabled by additive techniques and to educate the public in the environmental aspects of manufacturing. This will contribute to existing MIT educational programs for K-12 students, the local community, and, through massively open online courses, the wider world. Technical:This project addresses the cross-disciplinary factors necessary to make cellulose composites competitive and thus to advance the use of sustainable materials in manufacturing. The physical properties of cellulose composites are limited by the lack of understanding of how structure and interfacial bonding translate to mechanical behavior. This project studies study how biomimetic structuring of cellulose composites can enhance mechanical properties by local control of fiber alignment, porosity, and composition through a 3D printing process. Computational modeling is used to understand and predict optimal material architectures. Additionally, the project explores whether cellulose-bonding reversibility can enable a form of sustainable programmable matter. For these novel composites to contribute to global sustainability they will need to be adopted by industry and bring environmental benefits. In collaboration with Prof. Erica Fuchs of the Department of Engineering and Public Policy at Carnegie Mellon University, simulation modeling and empirical data will be used to compare the competitive position and environmental impact of additively manufactured biomimetic cellulose composites with glass fiber composites using prostheses as a case study. Comparing data on existing processes with the assumptions required to make the new materials competitive will elucidate how the technology must develop to become viable and the applications where it will have the greatest economic and environmental impact. The scientific focus of the project is on understanding structure-property relationships and subsequent formulation of rational strategies to enhance mechanical behavior in cellulose composites, which will also be applicable to other biomaterials and composites such as collagen or chitin. The ability to adapt biomaterial design principles by programming material properties across multiple length scales using 3D printing may also open a new avenue in the design of composites. This work will also advance understanding of how technology development can be guided towards viable applications using cost modelling.