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.

第一部分：非技术概述Swedish弹性体网络是聚合物材料，其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。这些包括生物软组织替代材料，例如在膝关节半月板或脊柱椎间盘中发现的材料，用于选择性去除化学或生物污染物的分离膜，用于电池技术的耐用和快速离子传输膜，以及设计用于提供长期冲击保护（军事，体育）同时保持高弹性柔性的材料。 然而，实践的简化一直受到满足这些应用所需的机械要求的能力有限的材料的困扰，这些材料经受弹性的快速衰减和对断裂失效的敏感性。该项目的重点是在溶胀弹性体网络设计中使用新的范例，以创建机械坚固的聚合物，能够在不疲劳的情况下维持重复的应力消散，同时抑制对断裂和故障的敏感性，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相结合。 它还将伴随着研讨会的发展，旨在建立世界各地顶级软物质合成和力学团体之间的合作，以推动科学前沿，探索新思想，并加速这些独特聚合物材料的未开发潜力。重要的是，研讨会将提供一个论坛，鼓励有才华的，但代表性不足的年轻研究人员，并为他们提供访问和指导，从领先的材料研究人员在世界上。第2部分：技术总结在过去十年中，在聚合物网络设计的创造性努力已经导致了许多有影响力的改进水凝胶力学。值得注意的实例包括高度弹性的水凝胶网络和高度耗散的水凝胶网络，在所述高度弹性的水凝胶网络中，疲劳最小但耗散非常少的能量，在所述高度耗散的水凝胶网络中，韧性最大化但疲劳快速并且恢复经受长的恢复时间（数分钟至数天）。然而，耗散能力和有效的弹性恢复的有效整合，似乎有限使用当前的设计策略。该提案的主要目的是证明结点形态（纳米结构）和链级组织控制的能力，以最大限度地提高非塑性能量耗散，恢复率，同时在溶胀的聚合物网络的抗疲劳性。所提出的研究的中心假设是，非键断裂耗散相互作用的合成集成到网络的每个分子链中，结合耗散机制与其自身的弹性恢复驱动力的隐式耦合，将增加大量的耗散能力，而不牺牲快速弹性恢复或特殊的抗疲劳性。该项目涉及独特设计的ABC和ABCBA嵌段共聚物的合成开发，这些嵌段共聚物在加热后自组装成基于核壳球形态的高效网络结构。目的是探索B嵌段结构域大小和疏水性程度成功地调节耗散能量大小的能力（例如，通过测量断裂韧性）并了解其对应变和应变速率的依赖性。如果成功，该项目将改变我们获得水凝胶材料的途径，这些材料既具有抗疲劳性，又具有韧性（体积和断裂），其恢复速度远远超过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。

项目成果

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

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.