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，由NSF科学、工程和教育可持续发展研究员(SEE FLOLS)计划赞助，目的是帮助实现必要的发现，为导致环境、能源和社会可持续发展的行动提供信息，同时培养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领域，它解决了在不损害环境、不牺牲子孙后代满足其需求的能力的情况下满足人类需求的挑战。一支强大的科学队伍需要接受跨学科研究和思维方面的教育和培训，特别是在可持续发展科学领域。在SEES奖学金的支持下，该项目将使一位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。该项目解决了复合材料在其高比强度和高硬度超过其生产成本的应用中日益普遍的使用问题。在要求苛刻的应用中使用可持续材料展示了添加剂系统如何在经济和环境方面增强制造过程。他与麻省理工学院机械工程系的John Hart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，研究纤维素源和处理方法的组合变异和原位表征，以识别和了解全纤维素复合材料中的结构变异。SEES研究员的重大职业发展将来自于获得新学科的经验，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，使其能够更广泛地参与由添加剂技术带来的产品设计机会，并在制造的环境方面教育公众。这将有助于麻省理工学院现有的面向K-12学生、当地社区的教育计划，并通过大规模开放的在线课程，扩大到更广泛的世界。技术：该项目涉及使纤维素复合材料具有竞争力，从而促进可持续材料在制造中的使用所必需的跨学科因素。由于缺乏对结构和界面结合如何转化为力学行为的了解，纤维素复合材料的物理性能受到限制。该项目研究了如何通过3D打印工艺对纤维的排列、孔隙率和组成进行局部控制，从而使纤维复合材料的仿生结构能够提高机械性能。计算建模用于理解和预测最优的材料结构。此外，该项目还探讨了纤维素键的可逆性是否能够实现某种形式的可持续可编程物质。为了让这些新型复合材料为全球可持续发展做出贡献，它们需要被工业界采用，并带来环境效益。与卡内基梅隆大学工程和公共政策系的Erica Fuchs教授合作，将使用模拟建模和经验数据来比较添加制造的仿生纤维素复合材料和使用假体的玻璃纤维复合材料的竞争地位和环境影响。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，以及它将在哪些方面产生最大的经济和环境影响。该项目的科学重点是了解结构与性能的关系，并随后制定合理的策略来增强纤维素复合材料的力学行为，这也将适用于其他生物材料和复合材料，如胶原或甲壳素。通过使用3D打印对多个长度尺度上的材料特性进行编程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。这项工作还将增进对如何利用成本模型引导技术发展走向可行应用的理解。

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.