RII Track-4: NSF: Understanding Microstructure Evolution in Stimuli-Responsive Yield-Stress Fluid-Assisted 3D Printing: Linking Microstructures to Macroscale Rheological Properties

RII Track-4：NSF：了解刺激响应屈服应力流体辅助 3D 打印中的微观结构演化：将微观结构与宏观流变特性联系起来

• 批准号: 2229004
• 负责人: Yifei Jin
• 金额: $ 23.18万
• 依托单位: Board of Regents, NSHE, obo University of Nevada, Reno
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-04-01 至 2025-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2229004&HistoricalAwards=false
• 关键词: RII; Track; NSF; Understanding; Microstructure

Recently, an innovative three-dimensional (3D) printing method has been proposed and developed to fabricate parts with arbitrary architectures. In this method, a 3D structure is freeform printed within a unique liquid support bath with desired properties that are controllable by either printing conditions or working environments. Although this method presents a better printing capability than many current 3D printing approaches, the working mechanisms of unique support bath materials are still elusive, which has hampered the further development of this 3D printing method. The project aims to investigate the microstructure changes of a representative thermosensitive support bath material at different temperatures and printing conditions. The achievements of this project can guide the design of more support baths as well as fundamentally explain the working mechanisms of printing within a support bath. The proposed research will have a profound societal impact by accelerating the development of 3D printing technology to enhance the manufacturing capability in the United States. In addition, the project will promote the education of students from K-12 to graduate in the State of Nevada through diverse activities, including hands-on K-12 lab activities, research module-involved curricula, and mentorship of students from underrepresented backgrounds at the University of Nevada, Reno. This Research Infrastructure Improvement Track-4 EPSCoR Research Fellows (RII Track-4) project would provide a fellowship to an Assistant professor and training for a graduate student at the University of Nevada Reno (UNR). Stimuli-responsive yield-stress fluids, developed on the basis of regular yield-stress materials, can change rheological properties/behaviors by responding to both applied shear stress and external stimuli. This dual-responsiveness makes stimuli-responsive yield-stress fluids promising for support bath-assisted 3D printing because a support bath material can be easily added during printing and removed after printing by applying external stimuli to achieve desired rheological properties, making it technically feasible to print 3D structures with arbitrary architectures. However, the interrelationships between microstructure evolution and macroscale rheology change of stimuli-responsive yield-stress fluids have so far remained elusive. Thus, the overarching goal of this project is to fundamentally understand the microstructure evolution of a representative stimuli-responsive yield-stress fluid—Pluronic F127-nanoclay nanocomposite—under different stress and temperature conditions through nanoscale material characterization, mathematical modeling, molecular dynamics simulation, and rheological testing. To achieve this goal, two integrated research objectives will be pursued: (1) characterize/establish static microstructure models in Pluronic F127-nanoclay nanocomposite via nanoscale material characterization techniques and mathematical modeling; and (2) explore temperature- and stress-induced microstructure evolutions via molecular dynamics simulation and rheological property testing. Completing the objectives will establish a paradigm for linking microstructures to macroscale rheological properties of support bath materials, promoting the development of more advanced stimuli-responsive yield-stress fluids for 3D printing applications in the future.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.

近年来，提出并发展了一种创新的三维打印方法来制造任意结构的零件。在这种方法中，3D结构在独特的液体支撑浴中自由打印，具有可通过打印条件或工作环境控制的所需性能。虽然该方法比目前许多3D打印方法具有更好的打印能力，但独特的支撑浴材料的工作机制仍然难以理解，这阻碍了该3D打印方法的进一步发展。本项目旨在研究一种具有代表性的热敏支撑浴材料在不同温度和打印条件下的微观结构变化。本项目的研究成果可以指导更多支撑槽的设计，并从根本上解释支撑槽内打印的工作机理。拟议的研究将通过加速3D打印技术的发展来提高美国的制造能力，从而产生深远的社会影响。此外，该项目将通过各种活动促进内华达州从K-12到毕业的学生的教育，包括动手K-12实验室活动，研究模块参与的课程，以及内华达大学里诺分校来自代表性不足背景的学生的指导。这项研究基础设施改善轨道4 EPSCoR研究研究员（RII轨道4）项目将为内华达大学里诺分校（UNR）的助理教授提供奖学金，并为研究生提供培训。刺激响应屈服应力流体是在常规屈服应力材料的基础上开发的，可以通过响应施加的剪切应力和外部刺激来改变流变特性/行为。这种双重响应性使得刺激响应屈服应力流体有望用于支撑浴辅助3D打印，因为支撑浴材料可以在打印过程中轻松添加，并在打印后通过施加外部刺激来实现所需的流变性能，从而在技术上可行地打印任意结构的3D结构。然而，迄今为止，屈服应力流体的微观结构演化与宏观流变变化之间的相互关系仍然是难以捉摸的。因此，该项目的总体目标是通过纳米材料表征、数学建模、分子动力学模拟和流变学测试，从根本上了解具有代表性的刺激响应屈服应力流体pluronic f127纳米粘土纳米复合材料在不同应力和温度条件下的微观结构演变。为了实现这一目标，将追求两个综合研究目标：(1)通过纳米级材料表征技术和数学建模来表征/建立Pluronic f127 -纳米粘土纳米复合材料的静态微观结构模型；(2)通过分子动力学模拟和流变性能测试，探索温度和应力诱导下的微观结构演变。完成这些目标将为支撑槽材料的微观结构与宏观流变特性之间的联系建立一个范例，促进未来3D打印应用中更先进的刺激响应屈服应力流体的开发。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。