Conjugated Polymer Nanocomposites

技术概述：将纳米颗粒结合到聚合物中是一种通用的材料设计方法，可用于材料科学的所有领域。该框架很有吸引力，因为它可以通过混合多种成分和利用协同效应来创造具有新的或改进性能的材料。纳米复合材料涉及电（半）导电共轭聚合物，因为它们的（光电）电子特性可以通过不同类型的材料组合而广泛地控制。由高纵横比共轭聚合物颗粒组成的纳米复合材料，即纳米纤维或纳米棒，可以提供许多特殊的特性，包括低浓度的渗透、各向异性和高内表面积，这对光伏应用非常重要。然而，很少有广泛适用的方法可以制造出个性化良好的共轭聚合物纳米纤维或棒及其纳米复合材料。由这项拨款支持的实验研究计划探索了一种新的、广泛有用的制造这种材料的框架。该方法依赖于纤维素纳米纤维的使用，它可以从几种生物来源中分离出来，作为高纵横比的纳米级支架。这些纤维素纳米纤维通过预先形成的聚合物的吸附、与小分子的反应或大分子的原位聚合，有策略地选择几种（半）导电聚合物和电活性小分子来修饰。这样制备的导电纳米纤维与“被动”载体聚合物一起加工成纳米复合材料，目的是制造出具有低渗透阈值的材料，即在低填料含量下具有高导电性。通过这种框架制备的半导体纳米纤维与其他共轭聚合物复合，目的是创建由两种不同半导体组成的共连续材料。这种具有高内表面积的半导体纳米复合材料在各种应用中都很受关注，包括光伏器件，这是本研究中探索的一个重要例子。加工新材料的一种方法是模板法。这种最近开发的制造方案是基于三维网络的形成，该网络是通过原本良好的个性化纳米纤维分散的凝胶化组装而成的。然后将凝胶化的纳米纤维模板与选定的聚合物一起吸收，然后将纳米复合材料干燥并成型。本程序的目的之一是证明模板方法是一种广泛适用的处理方法。非技术概述：包含一维（半）导电共轭纳米填料的聚合物纳米复合材料在从廉价导电塑料到高效聚合物太阳能电池的应用中具有广泛的应用前景。不幸的是，这些材料的生产非常具有挑战性。这项资助的实验研究探索了处理这些材料的新框架。由于其示范性和基础性，该研究有望为未来先进功能纳米材料的设计、加工和应用提供广泛的知识基础。跨学科的研究方法将使学生获得广泛的教育，并在聚合物科学与工程领域获得良好的知识基础。基础科学和应用研究的令人兴奋的组合将使他们在当今劳动力的最前沿。整合研究和教育的一个关键因素是形成所谓的项目研究团队，其中包括高中生、本科生和研究生以及教师。这辆车提供了一个令人兴奋的学习环境，并为研究生创造了教学和指导的机会。所有学生都将参加与克利夫兰自然历史博物馆和Shaker Heights学区合作的外展项目。这些活动将加强公众的科学和技术教育，并接触到当地社区非常多样化的受众。

TECHNICAL SUMMARY:The incorporation of nano particles into polymers is a general materials design approach that is employed in all areas of materials science. The framework is attractive because it enables the creation of materials with new or improved properties by mixing multiple constituents and exploiting synergistic effects. Nanocomposites involving electrically (semi)conducting conjugated polymers are of interest because their (opto)electronic properties can be widely manipulated through combination of different types of materials. Nanocomposites which comprise high-aspect ratio conjugated polymer particles, i.e. nanofibers or rods, can offer a number of special features, including percolation at low concentration, anisotropic properties, and high internal surface area, which is important for photovoltaic applications. However, few broadly applicable approaches are known that allow the fabrication of well-individualized conjugated polymer nanofibers or rods and nanocomposites thereof. The experimental research program supported by this grant explores a new, broadly useful framework for the fabrication of such materials. The approach relies on the use of cellulose nanofibers, which can be isolated from several biological sources, as a high-aspect ratio nano-scale scaffold. These cellulose nanofibers are decorated with several strategically chosen (semi)conducting polymers and electroactive small molecules through either adsorption of pre-formed polymers, reaction with small molecules, or in-situ polymerization of macromolecules. Electrically conducting nanofibers thus prepared are processed into nanocomposites with 'passive' carrier polymers with the objective to create materials that display low percolation threshold, that is, high electrical conductivity at low filler content. Semiconducting nanofibers prepared by this framework are compounded with other conjugated polymers with the objective to create co-continuous materials that are comprised of two different semiconductors. Such semiconducting nanocomposites with high internal surface areas are of interest in various applications, including photovoltaic devices, which are explored in this study as one important example. One method for the processing of the new materials is a template approach. This recently developed fabrication scheme is based on the formation of a three-dimensional network, which is assembled through the gelation of a dispersion of originally well-individualized nanofibers. The gelled nanofiber template is then imbibed with a polymer of choice, before the nanocomposite is dried and shaped. One objective of this program is to demonstrate that the template approach is a broadly applicable processing method.NON-TECHNICAL SUMMARY:Polymer nanocomposites comprising one-dimensional (semi)conducting conjugated nanofillers are of broad interest in applications that range from inexpensive conducting plastics to high efficiency polymer solar cells. Unfortunately, these materials are very challenging to produce. The experimental study supported by this grant explores a new framework for the processing of such materials. Because of its exemplary and fundamental character, the research is expected to provide a broad intellectual basis for the future design, processing and application of advanced functional nanomaterials. The interdisciplinary research approach will allow students to experience a broad education and to acquire a sound knowledge base in the area of polymer science and engineering. An exciting mix of fundamental science and applied research will place them at the cutting edge of today's workforce. One key element to integrated research and education is the formation of so-called Project Research Teams, which include high school students, undergraduate and graduate students, and faculty. This vehicle provides an exciting learning environment and creates teaching and mentoring opportunities for graduate students. All students will participate in outreach programs in collaboration with the Cleveland Museum of Natural History and the Shaker Heights School District. These activities will enhance the scientific and technological education of the public and reach out to a very diverse audience in the local community.