CAREER: Synthesis of Polymer Coated Magnetic Colloids and Assembly into Mesoscopic Nanoparticle Chains

技术概述：拟议的研究将侧重于开发一类新型有机/无机混合纳米颗粒，作为分层自组装材料的构建块。高分子包裹磁性纳米颗粒的合成、表征和组装的基本方面将是本提案的重点。所提出的研究的智力优点是能够制备具有分子，纳米和中尺度结构控制的复杂复合材料。开发一种多功能的合成方法来制备功能性铁磁胶体库将首先进行。该方法的核心是使用定义明确的聚合物来制备和功能化能够进行一维磁性组装的铁磁纳米颗粒。控制自由基聚合将是设计和合成聚合表面活性剂的核心。研究的第二个关键工作是在表面、溶液和聚合物薄膜上控制功能性铁磁纳米粒子的组装。将研究粒径、磁化强度和外加磁场的影响，以确定在各种矩阵中进行一维组装和对准的最佳条件。这些领域的发展有望使功能磁性纳米颗粒的组装和共价连接成为永久连接的链。这些功能的1-D组件有望成为聚合物链的中尺度类似物。利用各种成像技术（如原子力显微镜、透射电镜）、热分析和机械性能评估对这些材料进行表征，以确定具有不同形态的组装材料的结构-性能相关性。非技术概述：有机聚合物和金属颗粒将被合成并组合成具有可调组成的有机外壳和无机磁芯的核-壳复合材料。这些材料将在纳米尺度上杂交，作为制备具有协同性能的新型材料的一种方法。材料的磁性能将这些混合纳米粒子自组装成长度为微米的纤维状结构。由于能够在大范围的长度尺度上控制结构，这项工作预计将影响微电子和光电子器件的许多领域。拟议的研究是高度跨学科的，并为高中，本科和研究生水平的学生提供机会，以了解聚合物和纳米材料的重要性。由首席研究员在亚利桑那大学开展的研究经验中对高中学生和教师进行指导，将拟议的研究与教育外展相结合。该师生团队的研究将通过与校园本科生研究项目的整合互动进行传播。重点将放在图森少数族裔学生的指导和发展上。

TECHNICAL SUMMARY:The proposed research will focus on the development of a novel class of organic/inorganic hybrid nanoparticles as building blocks for hierarchically self-assembled materials. The fundamental aspects of the synthesis, characterization and assembly of polymer coated magnetic nanoparticles will be the focus of this proposal. The intellectual merit of the proposed research is the ability to prepare complex composite materials possessing controlled structure on molecular, nano- and mesoscale regimes. The development of a versatile synthetic methodology to prepare a library of functional ferromagnetic colloids will be initially pursued. Central to this approach is the use of well-defined polymers to prepare and functionalize ferromagnetic nanoparticles that are capable of 1-D magnetic assembly. Controlled radical polymerization will be central in the design and synthesis of polymeric surfactants. A second critical effort that will be investigated is the controlled assembly of functional ferromagnetic nanoparticle on surfaces, in solution and in polymer thin films. The effect of particle size, magnetization and applied magnetic fields will be investigated to determined optimal conditions for 1-D assembly and alignment in various matrices. Development of these areas is anticipated to enable the assembly and covalent linkage of functional magnetic nanoparticles into permanently linked chains. These functional 1-D assemblies are expected to be mesoscale analogues to polymer chains. Characterization of these materials using various imaging techniques (e.g., AFM, TEM), thermal analysis and mechanical property evaluation will be conducted to ascertain structure-property correlations of assembled materials possessing different morphologies. NON-TECHNICAL SUMMARY:Organic polymers and metallic particles will be synthesized and combined to prepare core-shell composite materials possessing an organic shell with tunable composition and an inorganic magnetic core. These materials will be hybridized on the nanoscale as an approach to prepare novel materials with synergistic properties. The magnetic properties of the materials will be utilized to self-assemble these hybrid nanoparticles into fiber-like structures spanning microns on length. This work is anticipated to impact a number of areas in microelectronics and optoelectronic devices due to the ability to control structure over a broad range of length scales. The proposed research is highly interdisciplinary and offers opportunities for students at high school, undergraduate and graduate levels to appreciate the importance of polymers and nanomaterials. Integration of the proposed research with educational outreach will be achieved by the mentoring of high school students and teachers in research experiences carried out at the University of Arizona by the principal investigator. Research implemented by this student-teacher team will be disseminated by integrated interactions with undergraduate research programs on campus. Emphasis will be placed on the mentoring and development of students from under-represented minorities in Tucson.