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

技术综述：拟议的研究将集中于开发一类新型的有机/无机杂化纳米颗粒，作为分层自组装材料的构建块。聚合物包覆磁性纳米粒子的合成、表征和组装的基本方面将是本提案的重点。这项研究的智力价值在于能够制备在分子、纳米和介观尺度上具有可控结构的复杂复合材料。首先将开发一种通用的合成方法来制备功能铁磁胶体的文库。这种方法的核心是使用定义明确的聚合物来制备能够进行一维磁性组装的铁磁性纳米颗粒并使其功能化。可控自由基聚合将在聚合物表面活性剂的设计和合成中发挥核心作用。将研究的第二项关键工作是在表面、溶液和聚合物薄膜中控制功能铁磁纳米颗粒的组装。将研究颗粒大小、磁化强度和外加磁场的影响，以确定在不同基质中进行一维组装和取向的最佳条件。这些领域的发展有望使功能性磁性纳米颗粒组装和共价连接成为永久连接的链。这些功能性的一维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、透射电子显微镜)对这些材料进行表征、热分析和机械性能评估，以确定具有不同形貌的组装材料的结构-性能相关性。非技术综述：有机聚合物和金属粒子将被合成并组合，以制备具有可调组成的有机外壳和无机磁性核心的核壳复合材料。这些材料将在纳米尺度上进行杂化，作为一种制备具有协同性能的新型材料的方法。这些材料的磁性将被用来将这些杂化纳米颗粒自组装成长度跨度为微米的纤维状结构。这项工作预计将影响微电子学和光电子器件的许多领域，因为它能够在广泛的长度范围内控制结构。这项拟议的研究是高度跨学科的，为高中、本科生和研究生提供了机会，让他们认识到聚合物和纳米材料的重要性。将通过由首席调查员指导高中生和教师在亚利桑那大学开展的研究经验，将拟议的研究与教育推广相结合。这个学生-教师团队实施的研究将通过与校园本科生研究项目的整合互动来传播。将把重点放在指导和发展图森市代表性不足的少数民族学生上。

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.