Basic Study on Novel Molecule-Based Magnetic Polymers and Homogeneous Magnetic Fluids

新型分子基磁性聚合物和均质磁性流体的基础研究

• 批准号: 0755763
• 负责人: Chang Han
• 金额: $ 31.44万
• 依托单位: University of Akron
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-02-01 至 2011-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0755763&HistoricalAwards=false
• 关键词: Basic; Study; Novel; Molecule; Based

CBET-0755763, HanThis research focuses on the design, synthesis, and characterization of molecule-based magnetic polymers having high Curie temperature (Tc). A series of monomers having tetracyano units or stable radicals (e.g., verdazyl radical or thioaminyl radical) for electron acceptor will be synthesized and each of the monomers will be reacted with a ferrocene- and biferrocene-containing monomer with long flexible side chains to obtain molecule-based magnetic polymers. Such polymers will form intramolecular exchange interactions through covalent bonding between the strong electron donor of ferrocene or biferrocene units along the macromolecular chains with the strong electron acceptor of tetracyano unit or stable radical. The intermolecular super exchange coupling will occur due to the polarization of both ferrocene (or biferrocene) units and tetracyano units (or stable radicals), and the entanglement of macromolecular chains will facilitate the expansion of one-dimensional spin coupling into a three-dimensional one. The magnetic properties of the polymers synthesized will be characterized using a magnetometer. X-ray diffraction will be employed to confirm that the polymers synthesized do not contain any impurities such as iron oxide, and electron spin resonance spectrometry will be employed to confirm the presence of spin interactions in the polymers synthesized. Owing to the presence of long flexible side chains on the ferrocene- or biferrocene-containing monomers used, such molecule-based magnetic polymers are expected to be soluble in common solvents. Such a prospect will ?open the door? to the development of a new generation of homogeneous magnetorheological (MR) fluids, quite different from the conventional MR fluids in current industrial use that are suspensions of very heavy magnetic particles (iron oxide or ferrite) in a light carrier liquid which are subject to serious problems of sedimentation and aggregation. The PI will investigate the fundamentals of the rheological behavior of a new generation of homogeneous MR fluids that will be prepared from the polymers synthesized in this research.INTELLECTUAL MERITAlthough small-molecule organic magnets having low Curie temperature (Tc) (much lower than room temperature) have been reported, during the past three decades many research groups have tried to develop truly molecule-based magnetic polymers having high Tc (much higher than room temperature). This research, if successful, will pave new frontiers in polymer synthesis, electronic structure chemistry, and materials chemistry, as well as stimulate theorists to develop new theory for magnetisms of macromolecules, since the currently available theories of magnetism deal with small-molecule organic magnets. High Tc molecule-based magnetic polymers may exhibit numerous desirable properties, including solubility, processability, and synthetic tenability, and could have practical applications. This project could provide new insights into how to design molecule-based magnetic materials having high Tc. It could also fundamentally advance the coordination chemistry of stable free radicals.BROADER IMPACTSThe research could have a broad impact on several scientific engineering disciplines including polymer chemistry, organometallic/coordination chemistry, condensed matter physics, and rheology for the development of a new theory for homogeneous MR fluids. Successful completion of the research project could lead to new method(s) for the synthesis of novel molecule-based magnetic polymers having high Tc, which do not exist at present, and can have an impact on manufacturing processes for a new generation of novel magnetic polymers and also the automotive industry that makes extensive use of magnetorheological fluids. The research will be highly interdisciplinary; graduate students will be exposed to a wide range of research experiences in the design and synthesis of novel polymers and their characterization, which will provide breadth and flexibility for their future careers.

CBET-075576​​3，Han这项研究重点是具有高居里温度（Tc）的分子基磁性聚合物的设计、合成和表征。 合成一系列具有四氰基单元或作为电子受体的稳定自由基（例如，四氮基或硫代氨基自由基）的单体，并且每种单体将与具有长柔性侧链的含二茂铁和联二茂铁的单体反应以获得分子基磁性聚合物。此类聚合物将沿着大分子链的二茂铁或联二茂铁单元的强电子给体与四氰基单元或稳定自由基的强电子受体之间通过共价键形成分子内交换相互作用。 由于二茂铁（或联二茂铁）单元和四氰基单元（或稳定自由基）的极化，会发生分子间超交换耦合，大分子链的缠结将有利于一维自旋耦合扩展到三维自旋耦合。 。 合成聚合物的磁性将使用磁力计进行表征。 X射线衍射将用于确认合成的聚合物不含任何杂质，例如氧化铁，并且电子自旋共振光谱法将用于确认合成的聚合物中自旋相互作用的存在。 由于所使用的含二茂铁或联二茂铁单体上存在长的柔性侧链，此类基于分子的磁性聚合物预计可溶于常见溶剂中。 这样的前景会“打开大门”吗？新一代均质磁流变 (MR) 流体的开发，与当前工业使用的传统 MR 流体截然不同，传统 MR 流体是非常重的磁性颗粒（氧化铁或铁氧体）悬浮在轻载液中，会受到严重的影响沉淀和聚集问题。 PI 将研究新一代均质 MR 流体的流变行为的基本原理，该流体将由本研究中合成的聚合物制备。据报道，在过去的三十年中，许多研究小组试图开发真正基于分子的具有高 Tc（远高于室温）的磁性聚合物。 这项研究如果成功，将为聚合物合成、电子结构化学和材料化学开辟新的前沿，并刺激理论学家发展大分子磁性的新理论，因为目前可用的磁性理论涉及小分子有机磁体。 基于高Tc分子的磁性聚合物可以表现出许多理想的特性，包括溶解性、可加工性和合成稳定性，并且可以具有实际应用。 该项目可以为如何设计具有高 Tc 的分子磁性材料提供新的见解。它还可以从根本上推进稳定自由基的配位化学。更广泛的影响这项研究可能对多个科学工程学科产生广泛影响，包括高分子化学、有机金属/配位化学、凝聚态物理和流变学，以开发均相新理论磁共振流体。该研究项目的成功完成可能会带来目前尚不存在的新型高Tc分子基磁性聚合物合成新方法，并对新一代新型磁性聚合物的制造工艺产生影响聚合物以及广泛使用磁流变液的汽车工业。 该研究将是高度跨学科的；研究生将接触到新型聚合物的设计和合成及其表征方面的广泛研究经验，这将为他们未来的职业生涯提供广度和灵活性。