Fighting Fatigue and Fracture with Morphologically Tuned Energy Dissipation in Highly Swollen Elastomer Networks

在高度膨胀的弹性体网络中通过形态调整能量耗散来对抗疲劳和断裂

• 批准号: 1808824
• 负责人: Travis Bailey
• 金额: $ 36万
• 依托单位: Colorado State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-07-01 至 2022-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1808824&HistoricalAwards=false
• 关键词: Fighting; Fatigue; Fracture; Morphologically; Tuned

PART 1: NON-TECHNICAL SUMMARYSwollen elastomer networks are polymeric materials that have the potential to play key roles in advancing of a number of health, energy, and environmental applications. These include biological soft-tissue replacement materials such as those found in the meniscus of the knee or the intervertebral disc of the spine, separation membranes for selective removal of chemical or biological contaminants, durable and rapid ion-transport membranes for battery technology, and materials designed to provide long-term impact protection (military, athletics) while retaining high elastic flexibility. Reduction to practice, however, has been plagued by materials with limited ability to meet the mechanical demands required of such applications, being subject to rapid decay in elasticity and susceptibility to failure by fracture. This project is focused on using a new paradigm in swollen elastomer network design to create mechanically robust polymers capable of sustaining repetitive stress dissipation without fatigue while suppressing susceptibility to fracture and failure needed to ensure long-term performance. The scientific advancement efforts in the project will be integrated with interdisciplinary education of students. It will also be accompanied by development of workshops aimed at building collaborations among top soft-matter synthesis and mechanics groups around the world, in an effort to push the frontiers of science, explore new ideas, and accelerate the untapped potential of these unique polymeric materials. The workshops importantly will provide a forum to encourage talented, yet underrepresented young researchers, and provide them access to and mentorship from leading materials researchers in the world.PART 2: TECHNICAL SUMMARYCreative efforts in polymer network design over the last decade have led to numerous impactful improvements in hydrogel mechanics. Notable examples include both highly elastic hydrogel networks in which fatigue is minimal but very little energy is dissipated, and highly dissipative hydrogel networks in which toughness is maximized but fatigue is rapid and recovery is subject to long recovery times (minutes to days). Effective integration of both dissipative capabilities and efficient elastic recovery, however, appears limited using current design strategies. The principal objective of this proposal is to demonstrate the ability of junction point morphology (nanostructure) and strand-level organizational control to maximize non-plastic energy dissipation, recovery rate, and fatigue resistance simultaneously in swollen polymer networks. The central hypothesis of the proposed research is that synthetic integration of non-bond rupturing dissipative interactions into every molecular strand of the network, combined with implicit coupling of the dissipation mechanism to its own driving force for elastic recovery, will add substantial dissipative capability without sacrificing the rapid elastic recovery or the exceptional fatigue resistance. The project involves the synthetic development of uniquely designed ABC and ABCBA block copolymers which upon heating self-assemble into highly efficient network structures based on core-shell sphere morphologies. The objectives are to explore the ability of the B block domain size and degree of hydrophobicity to successfully tune the magnitude of dissipated energy (e.g., through measurement of fracture toughness) and understand its dependence on strain and strain rate. If successful, this project will transform our access to hydrogel materials that exhibit both fatigue resistance and toughness (bulk and fracture), at rates of recovery far exceeding the most advanced hydrogel systems developed to date.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.

第1部分：非技术摘要弹性体网络是聚合物材料，具有在推进许多健康，能源和环境应用中发挥关键作用的潜力。其中包括生物软组织替代材料，例如在膝盖弯；脊柱的椎间盘中发现的材料，分离膜，用于选择性去除化学或生物学污染物，耐用和快速离子电波膜的电池技术，以及用于保持长期影响保护（军事影响力，竞技运动）的材料，并具有长期影响力的高级竞争力。 然而，减少实践的材料困扰着有限的材料满足此类应用所需的机械需求，这会导致弹性和因骨折失败的敏感性的快速衰减。该项目的重点是在肿胀的弹性体网络设计中使用新的范式，以创建能够在没有疲劳的情况下维持重复性压力消散的机械稳定的聚合物，同时抑制了对裂缝的易感性和所需的失败，以确保长期性能。 该项目的科学进步工作将与学生的跨学科教育融合。 它还将伴随着旨在在世界各地软体动物合成和机械群体之间建立合作的研讨会的发展，以推动科学领域，探索新思想并加速这些独特的聚合材料的未开发潜力。讲习班重要的是，将提供一个论坛，以鼓励才华横溢但不足的年轻研究人员，并为他们提供了世界领先的材料研究人员的访问和指导。第2部分：过去十年中聚合物网络设计中的技术摘要努力导致了Hydrogel Mechanics的许多有影响力的改进。值得注意的例子包括高度弹性的水凝胶网络，其中疲劳是最小的，但能量很少消散，并且高度耗散的水凝胶网络在其中韧性最大化，但疲劳是迅速的，并且恢复时间很长（分钟至几天）。然而，使用当前的设计策略有效地整合了耗散能力和有效的弹性恢复。该提案的主要目的是证明连接点形态（纳米结构）和链级组织控制的能力，以同时在肿胀的聚合物网络中同时同时提高非塑性能量耗散，恢复速率和疲劳抗性。拟议的研究的中心假设是，非键破裂的耗散相互作用的合成整合到网络的每个分子链中，结合了耗散机制与自身弹性恢复的隐式耦合，将增加实质性耗散能力，而无需牺牲快速的弹性恢复或出色的疲劳抵抗力或出色的疲劳抵抗。该项目涉及唯一设计的ABC和ABCBA嵌段共聚物的合成开发，这些共聚物在将自组装成基于核心壳球体形态的高效网络结构中时。这些目标是探索B块结构域大小和疏水程度成功调整消散能量的大小（例如，通过测量断裂韧性）的能力，并了解其对应变和应变速率的依赖。如果成功的话，该项目将改变我们对表现出抗疲劳性和韧性（体积和骨折）的水凝胶材料的获取，以恢复速度远远超过了迄今为止开发的最先进的水凝胶系统。该奖项反映了NSF的法定任务，并被认为是通过使用该基金会的知识分子功能和广泛影响来评估CRITERIA CRITERIA的评估。

项目成果

Self-assembly of highly asymmetric, poly(ionic liquid)-rich diblock copolymers and the effects of simple structural modification on phase behaviour

• DOI: 10.1039/c8py01414k
• 发表时间: 2019-02-14
• 期刊: POLYMER CHEMISTRY
• 影响因子: 4.6
• 作者: May, Alyssa W.;Shi, Zhangxing;Bailey, Travis S.
• 通讯作者: Bailey, Travis S.

Melt-Fabricated Photoreactive Block Copolymer Micelles as Building Blocks for Tunable Elastomeric Hydrogels

• DOI: 10.1021/acsapm.0c00108
• 发表时间: 2020-09
• 期刊: IEEE Transactions on Geoscience and Remote Sensing
• 影响因子: 8.2
• 作者: Nabila A. Huq;René P. M. Lafleur;Travis S. Bailey