RUI: Dynamic Guanidine-based Polymer Networks

RUI：动态胍基聚合物网络

• 批准号: 2105149
• 负责人: Michael Larsen
• 金额: $ 33万
• 依托单位: Western Washington University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-15 至 2025-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2105149&HistoricalAwards=false
• 关键词: RUI; Dynamic; Guanidine; based; Polymer

PART 1: NON-TECHNICAL SUMMARYPolymeric materials can generally be divided into two categories: (a) thermoplastics, materials such as plastic bottles, grocery bags, and nylon, that soften with heat and can be remolded and recycled; and (b) thermosets, those such as tires, epoxy adhesives, and resins, that have a permanent shape and are very difficult to reprocess. Thermosets thus have limited potential for reuse, ultimately having a negative impact on the environment through resource consumption and accumulation of large amounts of waste material. At the molecular level, the difference between these two classes of materials arises from the fact that thermoplastics consist of discrete polymer chains that can move and flow when heated, whereas thermosets are built from a crosslinked molecular network that is permanently bonded together. To bridge the gap between these materials, recent efforts have focused on making their fixed networks reversible -- that is, enabling them to de-crosslink under certain conditions followed by reformation of the network, allowing thermosets to be remolded and reprocessed. These systems represent a new class of materials known as dynamic polymer networks. While dynamic polymer networks have been the focus of considerable research during the last two decades, many fundamental questions about them remain, detracting from their practical utility and restricting their applications beyond the research lab. This research will leverage the unique characteristics of a novel chemical reaction aimed at de-crosslinking thermosets in order to gain generalized insight into the fundamental principles of dynamic polymer networks. Successful realization of the PI’s research goals will yield a wide variety of reprocessable thermosets and link specific molecular-level characteristics with macroscopic properties, helping to shape future designs and applications of these advanced materials in areas as varied as sustainable manufacturing, advanced medicine, and next-generation batteries. Students participating in this research will be trained in an interdisciplinary manner involving synthetic chemistry, polymer characterization, and a variety of techniques for property determination.PART 2: TECHNICAL SUMMARYDynamic polymer networks are covalently crosslinked materials that combine the desirable properties of thermosets with the reprocessability of thermoplastics. Their crosslinks undergo reversible exchange reactions that are activated under specific conditions, continuously reorganizing the network. Recently the PI demonstrated a new type of these materials based on previously unknown exchange reactions of guanidines. This proposal seeks to leverage the unique capabilities of dynamic guanidine-based polymer networks to answer fundamental questions in the field of dynamic materials and expand the window of achievable properties of these systems. Specific objectives of this proposal are to: (1) use the versatility of the guanidine functionality to both modify its reactivity and introduce noncovalent bonding partners, establishing the link between fundamental molecular-scale properties and macroscopic rheological behavior; and (2) incorporate guanidine crosslinks into a variety of precisely altered polymer structures to elucidate the role of specific characteristics of the “background” polymer in determining the behavior of dynamic networks. These studies will be accomplished by student researchers using a combination of synthetic techniques, polymer characterization, rheological analysis, and dielectric spectroscopy..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：非技术摘要材料通常可以分为两类：（a）热塑性塑料，诸如塑料瓶，杂货袋和尼龙等材料，可以随热而变软，可以重新恢复并回收； （b）具有永久形状且难以重新处理的温度，诸如轮胎，环氧胶粘剂和树脂之类的热眠剂。因此，热眠者的重复使用潜力有限，最终通过资源消耗和大量废物的积累对环境产生负面影响。在分子水平上，这两类材料之间的差异是由热塑性塑料组成的事实，是由离散的聚合物链组成，在加热时可能会移动和流动，而热固件是由永久键合的交联的分子网络构建的。为了弥合这些材料之间的差距，最近的努力集中在使其固定网络可逆 - 也就是说，使它们能够在某些条件下脱离交叉链接，然后再进行网络改革，从而使热固件可以重新恢复和重新处理。这些系统代表了一种新的材料，称为动态聚合物网络。在过去的二十年中，动态聚合物网络一直是考虑研究的重点，但有关它们的许多基本问题仍然存在，损害了它们的实际效用，并将其应用限制在研究实验室之外。这项研究将利用旨在取消连接热固体的新型化学反应的独特特征，以便获得对动态聚合物网络的基本原理的广泛见解。 PI研究目标的成功实现将产生各种可重复的热固体，并将特定的分子水平特征与宏观特性联系起来，从而有助于塑造这些高级材料在可持续制造，高级医学和下一代电池中的各种区域的未来设计和应用。参与这项研究的学生将以跨学科的方式进行培训，涉及合成化学，聚合物表征和各种物业确定的技术。第2部分：技术摘要的聚合物网络是共价交联的材料，这些材料结合了热量与热型的重新处理能力相结合的材料。它们的交联经历了在特定条件下激活的可逆交换反应，并不断重组网络。最近，PI基于以前未知的鸟甲啶的交换反应，展示了这些材料的新型材料。该提案旨在利用动态鸟嘌呤的聚合物网络的独特功能来回答动态材料领域的基本问题，并扩大这些系统可实现的属性的窗口。该提案的具体目标是：（1）使用鸟根功能的多功能性来修改其反应性又引入非共价键合伙伴，建立了基本分子尺度特性与宏观流变学行为之间的联系； （2）将鸟选择链链接纳入各种精确改变的聚合物结构中，以阐明“背景”聚合物在确定动态网络行为中的特定特征的作用。这些研究将由学生研究人员使用合成技术，聚合物表征，流变学分析和饮食光谱的结合来完成。该奖项反映了NSF的法定任务，并被认为是通过基金会的智力优点和更广泛的影响审查标准来评估的支持。