Reaction Directed Polymer Nanostructures through Self-Assembly and Photopolymerization

0933450盖蒙该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。自组织液晶的使用是一种通过纳米尺度上的结构和化学控制来增强有机聚合物性能的方法。 基于溶致的功能纳米结构聚合物材料（即，两亲性）液晶（LLC）具有在水存在下自组织成具有周期性纳米级多孔域的有序组装体的能力。聚合的LLC单体和由LLC模板化的聚合物最近在诸如固态有机催化剂、尺寸选择性膜和组织工程支架的应用中显示出巨大的前景。使用LLC系统形成纳米结构聚合物的主要障碍是难以在整个聚合过程中保持和控制自组装结构。通常，在聚合期间发生结晶驱动的相分离，留下很少或没有液晶有序。PI计划控制热力学和动力学因素，以指导LLC材料的特定聚合物纳米结构。智力优势：目标是利用聚合反应通过光聚合和最佳LLC自组装的组合来引导有机聚合物纳米结构。研究将集中于开发形成LLC相的非反应性和反应性表面活性剂系统的组合。然后，这些系统将用于模板有序形态到聚合物网络。将监测跨越各种LLC相的材料的光聚合，以了解它们在聚合期间发生的顺序的变化。可能影响聚合物形态的因素，包括LLC相结构和稳定性，交联密度，和聚合动力学将被检查。据推测，自由基光聚合的使用将在这项工作中发挥关键作用。该方法提供了在宽范围的温度下在几分之一秒内捕获的能力，从而允许动力学捕获否则在化学上不利的聚合物纳米结构。聚合物结构形成从传统的链和硫醇烯逐步增长聚合机制将进行研究。随着纳米结构在本项目中的重要性，一些强大的表征工具（偏振光显微镜，X射线衍射，扫描电子显微镜，透射电子显微镜，固态NMR和溶胀行为）将用于阐明聚合过程中和聚合后的聚合物结构。在这项研究工作中取得成功的关键是彻底了解光聚合过程，包括纳米结构环境引起的独特方面。因此，将使用光差示扫描量热法、红外和拉曼光谱实时监测光聚合动力学和双键转化。所获得的结果将概述的因素，动力学和热力学，可用于管理和指导最终的聚合物纳米结构。更广泛的影响：纳米技术最大的希望之一是能够控制基于有机聚合物纳米级结构的性能。这项工作将产生纳米结构的可重复性和一致性的基础上LLC的几何形状。利用光聚合的固有速度和整个聚合过程中的最佳自组装，将提供基于纳米尺度几何形状的聚合物性能控制。通过这种控制，可以实现在分离技术、药物递送、催化、水凝胶和组织工程等多种应用中的实质性进步。该项目的一个主要主题将是学生教育。将强调本科生和研究生研究人员在发现学习环境中的广泛参与。PI在研究生和本科生阶段都有包括少数民族学生研究人员的良好记录。至少有一名少数民族研究生将直接参与研究，少数民族本科研究人员将被招募作为爱荷华州大学AGEP夏季研究计划的一部分。此外，聚合物在纳米技术中的重要性将作为PI每年向当地和农村高中化学课提供的模块的一部分带给高中生。

0933450GuymonThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The use of self-organizing liquid crystals is a method of enhancing performance of organic polymers through structural and chemical control on the nanometer scale. Functional nanostructured polymer materials based on lyotropic (i.e., amphiphilic) liquid crystals (LLCs) have the ability to self-organize in the presence of water into ordered assemblies with periodic nanometer-scale porous domains. Both polymerized LLC monomers and polymers templated by LLCs have recently shown great promise in applications such as solid-state organic catalysts, size selective membranes, and tissue engineering scaffolds. The major obstacle in forming nanostructured polymers using LLC systems is the difficulty in retaining and controlling the self-assembled structure throughout the polymerization. Typically, thermodynamically driven phase separation occurs during polymerization, leaving little or no liquid crystalline order. The PI plans to control both thermodynamic and kinetic factors to direct specific polymer nanostructures from LLC materials. Intellectual Merit: The goal is to utilize the polymerization reaction to direct organic polymer nanostructures through combination of photopolymerization and optimal LLC self-assembly. Research will focus on developing combinations of non-reactive and reactive surfactant systems that form LLC phases. These systems will then be used to template ordered morphology onto polymer networks. The photopolymerization of materials spanning a wide range of LLC phases will be monitored to understand changes in the order that they occur during polymerization. Factors that may influence polymer morphology including LLC phase structure and stability, cross-link density, and polymerization kinetics will be examined. It is assumed that the use of radical photopolymerization will play a pivotal role in this work. This method provides the ability to polymerize in fractions of a second at a wide range of temperatures, thereby allowing kinetic trapping of otherwise thermodynamically unfavorable polymer nanostructures. Polymer structures formed from both traditional chain and thiol-ene step growth polymerization mechanisms will be investigated. With the importance of nanostructure in this project, a number of powerful characterization tools (polarized light microscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, solid state NMR, and swelling behavior) will be used to elucidate polymer structure during and after polymerization. Critical for success in this research effort is a thorough understanding of the photopolymerization process, including the unique aspects induced by a nanostructured environment. Therefore, photopolymerization kinetics and double bond conversion will be monitored in real-time using photo-differential scanning calorimetry, infra-red and Raman spectroscopy. The results obtained will outline the factors, both kinetic and thermodynamic, that can be used to govern and direct the ultimate polymer nanostructure. Broader Impact: One of the greatest promises of nanotechnology is the ability to control properties based on nano-scale architectures in organic polymers. This work will produce nanostructures reproducibly and consistently based on LLC geometries. Using the inherent speed of photopolymerization and optimal self-assembly throughout polymerization, control of polymer properties based on nano-scale geometries will be afforded. With such control substantial advances in applications as diverse as separation technology, drug delivery, catalysis, hydrogels, and tissue engineering could be realized. A prevailing theme in the project will be student education. Extensive involvement of undergraduate and graduate researchers in a discovery learning environment will be emphasized. The PI has a strong record of including minority student researchers at both the graduate and undergraduate level. At least one minority graduate student will directly participate in the research, and minority undergraduate researchers will be recruited as part of the AGEP Summer Research Program at the University of Iowa. Additionally, the importance of polymers in nanotechnology will be brought to high school students as part of a module presented yearly by the PI to chemistry classes at both local and rural high schools.