Collaborative Research: Exploring the Role of Ultra-Soft Inclusions in the Mechanics of Fibrous Materials

在自然界中，生物组织等纤维材料可以表现出适应性行为。这些包括可调的密度、硬度和渗透性，使它们能够承载机械载荷，对环境刺激做出反应，并治愈伤口。这些行为是通过细胞和血小板等超软包涵体以及它们与周围纤维网络的相互作用实现的，共同赋予其宿主材料特殊的功能。要在工程材料中模拟这样的功能，需要深入了解超软夹杂物在大变形时纤维网络中的力学作用。该奖项支持有关超软夹杂物如何与纤维网络相互作用以及这些小规模相互作用如何影响主体材料的整体变形行为的基础研究。这项研究的结果不仅将为设计和制造生物启发的适应性材料提供新的见解，使其在智能纺织品和可穿戴技术、伤口愈合、滤膜和软机器人等方面得到广泛应用，而且还将有助于更好地了解生物组织中由细胞和细胞状颗粒形式的超软包裹体驱动的生理和病理过程，从而促进国家的健康、繁荣和福利。除了使更广泛的科学界受益外，这项工作还将通过新的跨学科课程模块、研究机会和跨机构访问计划来支持本科生和研究生教育。另一个更广泛的影响将是通过与德克萨斯州奥斯汀国防部附属的STEM青年计划合作针对中学生的教育推广计划，激励学生认识到从生物医学工程到土木工程和机械工程的许多工程原理的普遍性。微米大小的超软夹杂物在天然材料中普遍存在，尽管尺寸很小，但在整体机械性能中发挥着关键作用。该奖项旨在了解高度可变形夹杂物与半柔性纤维网络的受控微尺度、局部和非局部相互作用如何导致工程材料在宏观尺度上的涌现行为。重点放在聚合物(纤维)主体材料，因为它们在工程应用和自然的重要性。计算方法结合了考虑体粘附力和表面粘附力、弹性毛细管效应、软固体梁接触现象和数据驱动的均匀化的表面丰富的数值工具来预测聚合物-颗粒复合材料的力学。重要的是，该项目开发了一种可控的实验微凝胶平台，以制造和研究具有高度可调机械性能的超软夹杂物。使用微凝胶材料平台的理论、计算和微观和宏观实验之间的迭代反馈回路是验证预测和通知模型开发的项目的核心。最终，这个项目将提供一个定量的知识库和一个微凝胶合成平台，以证明通过控制超软夹杂物和纤维网络之间的非线性局部/非局部相互作用，可以精确地调整含有超软夹杂物的复合材料的材料设计空间。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。

In nature, fibrous materials such as biological tissues can display adaptive behaviors. These include tunable density, stiffness, and permeability, which allow them to carry mechanical loads, respond to environmental stimuli, and heal wounds. These behaviors are achieved through ultra-soft inclusions like cells and platelets, and their interactions with the surrounding fibrous network, collectively lending their host materials specialized functions. Mimicking such functions in engineered materials requires a deep understanding of the mechanical role of ultra-soft inclusions in fiber networks at large deformations. This award supports fundamental research on how ultra-soft inclusions interact with a network of fibers and how these small-scale interactions affect the overall deformation behavior of the host material. The findings from this investigation will not only provide new insights into the design and fabrication of bio-inspired, adaptive materials for diverse applications in smart textiles and wearable technology, wound healing, filtration membranes, and soft robotics, but it will also lead to a better understanding of physiological and pathological processes in biological tissues that are driven by ultra-soft inclusions in the form of cells and cell-like particles, consequently advancing the national health, prosperity, and welfare. In addition to benefitting the broader scientific community, this work will also support undergraduate and graduate education through new, interdisciplinary class modules, research opportunities, and a trans-institutional visitation program. An additional broader impact will be through an education outreach program aimed at middle school students in collaboration with a Department of Defense-affiliated STEM youth program in Austin, TX, inspiring the students to recognize the universality of many engineering principles spanning from biomedical engineering to civil and mechanical engineering.Micron-sized, ultra-soft inclusions in fiber networks are ubiquitous in natural materials and play a critical role in the overall mechanical properties despite their small size. This award aims to understand how controlled microscale, local and non-local interactions of highly deformable inclusions with semi-flexible fiber networks lead to emergent behaviors at macroscales in engineered materials. The focus is on polymeric (fibrous) host materials for their importance in both engineering applications and nature. Computational approaches combine surface-enriched numerical tools accounting for bulk and surface adhesion, elastocapillary effects, soft solid-beam contact phenomena, and data-driven homogenization to predict the mechanics of polymer-particle composites. Critically, this project develops a controllable, experimental microgel platform to make and study ultra-soft inclusions with highly tunable mechanical properties. An iterative feedback loop between theory, computations, and micro- and macroscale experiments using the microgel material platform is central to the project for validating predictions and informing the model development. Ultimately, this project will provide a quantitative knowledge base and a microgel synthesis platform to demonstrate that the material design space of composites with ultra-soft inclusions can be precisely tuned through control of the nonlinear local/nonlocal interactions between ultra-soft inclusions and fibrous networks.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.