RUI: Metal-Coordination Crosslinked Polymer Networks as Elastomers

非技术总结：这项主要由本科院校（RUI奖）进行的研究重点是开发一种新型聚合物橡胶材料，与商业橡胶材料不同，这种材料是可回收的。用于制造这种新材料的化学物质也将允许使用电力打开和关闭橡胶特性。一个成功的项目的结果将是一种可以从液体转化为橡胶的材料，只需按一下开关。此外，这些材料可以被设计成显示一种颜色，表明材料是否是橡胶。当材料被化学、电或机械削弱时，颜色会发生变化，以提供视觉警告，表明材料可能无法像预期的那样工作。这种新型材料可以实现新技术，如电控橡胶，用于先进的振动/冲击阻尼系统或在需要更换时改变颜色的垫圈。除了潜在的新技术之外，这项研究还将在三年内为多达20名本科生提供高级研究培训。它还将扩大阿巴拉契亚州立大学的材料研究基础设施，使那里的教师能够在未来几年继续进行材料研究。技术概述：在本研究项目中，将合成2,2'-联吡啶端部聚（二甲基硅氧烷）（PDMS）链，并与各种金属盐（如铁（II）氯化物）混合，以形成金属配位络合物交联聚合物网络（MC3PN）。这些MC3PN随后将用紫外/可见光谱、循环伏安法、差示扫描量热法和动态力学分析来表征，以更好地了解分子结构与所得性质之间的关系。在拟议的研究过程中，将寻求以下五个问题的答案。1)金属-配体结合是否足够稳定，可以作为交联并在室温下赋予MC3PN弹性性能？2)是否可以改变网络结构（如交联密度）来定制弹性体MC3PNs的机械性能，就像可以定制传统共价交联弹性体性能（如刚度和强度）一样？3)金属配位配合物能否通过引入螯合配体、氧化还原过程或温度变化而可逆和可控地非交联？4)金属配位配合物赋予MC3PNs的颜色是否可以用来确定材料的交联程度，并由此推断机械性能（如材料即将失效）？5)金属配合物的自组装能否赋予弹性体材料自修复性能？除了潜在的新技术之外，这项研究还将在三年内为多达20名本科生提供高级研究培训。它还将扩大阿巴拉契亚州立大学的材料研究基础设施，使那里的教师能够在未来几年继续进行材料研究。

NON-TECHNICAL SUMMARY:This research in a primarily undergraduate institution (RUI award) is focused on the development of a new type of polymeric rubber material which, unlike commercial rubber materials, would be recyclable. The chemistry used to make this new material also would allow for the rubbery properties to be turned on and off using electricity. The result of a successful project would be a material that could be converted from a liquid to a rubber at the flip of a switch. Additionally, these materials could be designed to display a color that indicates whether the material is rubbery or not. The color would change when the material has been chemically, electrically, or mechanically weakened to provide a visual warning that the material may not work as expected. This new class of materials could enable new technologies such as electrically controlled rubbers for use in advanced vibration/impact damping systems or in gaskets that change color when in need of replacement.Beyond potentially enabling new technologies, the pursuit of this research will allow for advanced research training of up to 20 undergraduate students over three years. It will also expand the materials research infrastructure at Appalachian State University, enabling faculty there to continue materials research for years to come. TECHNICAL SUMMARY:In this research project, 2,2'-bipyridine-terminated poly(dimethylsiloxane) (PDMS) chains will be synthesized and blended with various metal salts (e.g. iron (II) chloride) to create metal coordination complex crosslinked polymer networks (MC3PN)'s. These MC3PN's will subsequently be characterized with UV/Vis spectroscopy, cyclic voltammetry, differential scanning calorimetry, and dynamic mechanical analysis to better understand the relationship between the molecular structure and the resulting properties. In the course of the proposed research, the answers to the following five questions will be sought. 1) Is the metal-ligand binding sufficiently stable to serve as crosslinks and impart the MC3PN with elastomeric properties at room temperature? 2) Can altering the network structure (e.g. cross-link density) be used to tailor the mechanical properties of the elastomeric MC3PNs in the same manner that conventional covalently crosslinked elastomer properties (e.g. stiffness and strength) can be tailored? 3) Can the metal coordination complexes be reversibly and controllably un-crosslinked through the introduction of chelating ligands, redox processes, or a change in temperature? 4) Can the color imparted to the MC3PNs by the metal coordination complexes be used to ascertain the degree to which the material is crosslinked and from this to infer the mechanical properties (such as impending failure of the material)? 5) Can the self-assembly of metal coordination complexes impart self-healing properties to the elastomeric material?Beyond potentially enabling new technologies, the pursuit of this research will allow for advanced research training of up to 20 undergraduate students over three years. It will also expand the materials research infrastructure at Appalachian State University, enabling faculty there to continue materials research for years to come.