Collaborative Research: Electron Transport Membranes using Nanostructured Block Copolymer Assemblies

0932311 Jeffries-EL智力优点：共轭（导电）聚合物的纳米级控制尤其重要，因为此类功能材料的形态在器件性能中起着重要作用，影响诸如导电性、热稳定性、加工性和机械完整性等性能。该提案的目标是为有机电子器件创建新的聚合物网络材料，由于形成了明确定义和连续的纳米级导电通路，因此具有更好的性能。这一目标将通过将近单分散导电聚合物（区域规则聚（3-烷基噻吩）（rr-P3 AT））的合成与嵌段共聚物（BCP）的天然自组装相结合来实现，以产生具有形成多个连续组装体的能力的新型聚合物材料。这项建议有两个具体目标。首先，将合成含有导电嵌段的新型网络形成ABC三嵌段共聚物。这些材料将被设计成使得它们含有产生界面曲率和鞍形表面所必需的嵌段共聚物体积分数，这是纳米级网络的标志。此外，聚合物的化学连接性将被设计为使得导电（棒）嵌段的结晶受到限制，以保持网络形态。接下来，膜结构将通过散射，显微镜和机械分析技术进行表征;膜电导率（和流动性）也将使用四点探针测量和介电光谱进行检查。所提出的纳米级网络形态具有相对于层和圆柱形通道的上级机械属性，并且它们的膨胀互连域和大的界面面积提供了产生具有定制的传输、化学和机械性质的导电材料的机会。这些因素将导致聚合物共混物系统的显著改进，在聚合物共混物系统中，形成均匀尺寸的连续传导和传输路径是提高聚合物器件效率的关键障碍。在有机薄膜中产生连续的纳米级导电通路的能力对于有机材料的进一步开发和使用至关重要，因为畴边界处的差的电子性质通常限制了整体性能。设备属性。这对于发光二极管（LED）、薄膜晶体管（TFT）和光致发光器件（PV）尤其重要，其中改进的传输在这些器件的电子活性层中是必不可少的。虽然文献中已经报道了rr-P3 AT BCP的合成，但这项工作旨在创新其设计。具体地，上述共聚物将包含赋予韧性的一个嵌段;提供可结晶嵌段的限制的第二嵌段;和可结晶且导电的第三嵌段。这项工作的一个新的方面是，导电rr-P3 AT嵌段的化学已被修改，以降低结晶温度，使结晶不会改变整体自组装嵌段共聚物结构。拟议的研究将提供新的见解棒线圈嵌段共聚物组成，形态和电子性能之间的相互作用。总的来说，这有望导致CP形态和电子性质的优化。此外，这个跨学科项目将培训研究生和本科生，以解决纳米技术的关键科学和工程挑战。具体的更广泛的影响和教育举措侧重于提高代表性不足群体的参与。其中包括：通过PI参与ACS多样性合作伙伴计划和少数民族学者计划，提供夏季研究和指导机会。此外，联合PI参与爱荷华州州立大学[ISU]的几个项目（AGEP、新生荣誉和NOBCChE）将用于从代表性不足的群体中招募研究生到ISU。最后，我们建议交换学生之间的特拉华州，化学工程系，和ISU，化学系，以扩大他们的研究知识基础。

0932311Jeffries-ELIntellectual Merit: Nanoscale control of conjugated (conducting) polymers is especially important as the morphology of such functional materials plays a significant role in device performance, influencing properties such as conductivity, thermal stability, processability, and mechanical integrity. The goal of this proposal is to create new polymeric network materials for organic electronics devices, with improved performance due to the formation of well defined and continuous nanoscale conducting pathways. This goal will be achieved by combining the synthesis of near monodisperse conducting polymers (regioregular poly(3-alkylthiophenes) (rr-P3AT)s ), with the natural self assembly of block copolymers (BCPs) to create novel polymeric materials with the ability to form multiply continuous assemblies. There are two specific aims of this proposal. First, novel network forming ABC triblock copolymers containing an electrically conductive block will be synthesized. These materials will be designed such that they contain the block copolymer volume fractions necessary to generate the interfacial curvature and saddle surfaces, which are a hallmark of nanoscale networks. In addition, the chemical connectivity of the polymer will be designed such that crystallization of the conducting (rod) block is confined in order to maintain the network morphology. Next, membrane structures will be characterized by scattering, microscopy, and mechanical analysis techniques; membrane conductivity (and mobility) also will be examined using four point probe measurements, and dielectric spectroscopy. The proposed nanoscale network morphologies have superior mechanical attributes, relative to layers and cylindrical channels, and their percolating interconnected domains and large interfacial area present the opportunity to create conducting materials with tailored transport, chemical, and mechanical properties. These factors will lead to a dramatic improvement over polymer blend systems, where the creation of uniform-sized continuous pathways for conduction and transport is a key hurdle to improving the efficiency of polymeric devices.Broader Impact: The ability to create continuous nanoscale conducting pathways in organic thin films is crucial for further development and use of organic materials because poor electronic properties at domain boundaries often limit overall device properties. This is of particular concern for light emitting diodes (LEDs), thin-film transistors (TFTs), and photovoltaics (PVs), where improved transport is essential in the electronically active layers of these devices. While the synthesis of rr-P3AT BCPs has been reported in the literature, this work seeks to innovate their design. Specifically, the copolymers described above will contain one block that imparts toughness; a second block to provide confinement of the crystallizable block; and a third block that is crystallizable and conducting. A novel aspect of this work is that the chemistry of the conducting rr-P3AT block has been modified to lower the crystallization temperature, so that crystallization does not alter the overall self assembled block copolymer structure. The proposed research will provide new insights into the interplay between rod coil block copolymer composition, morphology and electronic properties. Collectively, this is expected to result in the optimization of CP morphology and electronic properties. Furthermore, this interdisciplinary project will train graduate and undergraduate students to address key scientific and engineering challenges in nanotechnology. Specific broader impact and educational initiatives are focused on increasing the participation of under represented groups. These include: providing summer research and mentorship opportunities through the PI's involvement with the ACS Diversity Partner Program and Minority Scholars Program. Additionally, the co-PI's involvement with several programs at Iowa State University [ISU] (AGEP, Freshman Honors, and NOBCChE) will be used to recruit graduate students from under represented groups to ISU. Finally, we propose the exchange of students between the University of Delaware, Chemical Engineering Department, and the ISU, Department of Chemistry, to broaden their research knowledge base.