Kinetic Control of Polymer Nanostructure in Lyotropic Liquid Crystalline Systems

溶致液晶体系中聚合物纳米结构的动力学控制

• 批准号: 0626395
• 负责人: Allan Guymon
• 金额: --
• 依托单位: University of Iowa
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-15 至 2013-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0626395&HistoricalAwards=false
• 关键词: Kinetic; Control; Polymer; Nanostructure; Lyotropic

ABSTRACTPI: Allan Guymon Institution: University of IowaProposal Number: 0626395Title: Kinetic Control of Polymer Nanostructure in Lyotropic Liquid Crystalline SystemsProject Summary: The use of self-organizing liquid crystals is a means of achieving structural and chemical control of organic polymers on the nanometer scale for enhanced performance. One area that has recently received a great deal of interest is the development of functional nanostructured polymer materials based on lyotropic (i.e., amphiphilic) liquid crystals (LLCs) which 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 using polymerized LLC materials is the ability to retain and control this structure throughout the polymerization. Typically, thermodynamically driven phase separation occurs during polymerization, leaving little or no liquid crystalline order. The polymerization kinetics in LLC systems are highly dependent on order, but the direct correlation between the polymerization rate and ultimate polymer nanostructure has not been explored.Intellectual Merit: The goal of this research is to use the speed of photopolymerization to predict and control the nanostructure produced in LLC systems. Research will focus on reactive surfactant monomers that form LLC phases and both polar and non-polar monomers templated by nonreactive LLCs. The photopolymerization of materials spanning a wide range of LLC phases will be monitored to understand changes that occur during polymerization. Factors that may influence polymer morphology including LLC phase structure and stability, cross-link density, monomer polarity, and double bond location will be examined. Radical photopolymerization 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. Polymers 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, and scanning electron microscopy) will be used to elucidate polymer structure. 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 facilitate development of a complete model outlining the factors, both kinetic and thermodynamic, governing the ultimate polymer nanostructure.Broader Impact: One of the most promising advances that could result with the recent emphasis on nanotechnology is the ability to control properties based on nano-scale architectures produced in organic polymers. This work proposes methods to reproducibly produce nanostructures based on LLC geometries using the inherent speed of photopolymerization allowing control of polymer properties based on nanoscale geometries. If such control can be achieved, substantial advances in applications as diverse as separation technology, hydrogels, and tissue engineering could be realized. A prevailing theme 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 proposed 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 by the PI to chemistry classes at both local and rural high schools.

摘要：Allan Guymon机构：Iowa大学提案号：0626395题目：溶致液晶体系中聚合物纳米结构的动力学控制项目摘要：自组织液晶的使用是在纳米尺度上实现有机聚合物的结构和化学控制以增强性能的一种手段。 最近受到极大关注的一个领域是基于溶致（即，两亲性）液晶（LLC），其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。使用聚合的LLC材料的主要障碍是在整个聚合过程中保持和控制这种结构的能力。 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。 LLC系统中的聚合动力学高度依赖于顺序，但聚合速率和最终聚合物nanostructures之间的直接相关性尚未explored.Intellectual Merit：本研究的目标是使用光聚合的速度来预测和控制在LLC系统中产生的纳米结构。 研究将集中于形成LLC相的反应性表面活性剂单体以及由非反应性LLC模板化的极性和非极性单体。 将监测跨越各种LLC相的材料的光聚合，以了解聚合过程中发生的变化。 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、单体极性和双键位置将被检查。 自由基光聚合提供了在宽范围的温度下以几分之一秒的时间进行聚合的能力，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射线衍射和扫描电子显微镜）将用于阐明聚合物结构。 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。 所获得的结果将有助于开发一个完整的模型，概述了动力学和热力学的因素，支配最终的聚合物nanostructure.Broader的影响：最有前途的进步，可能导致与最近强调纳米技术是能够控制性能的基础上产生的有机聚合物的纳米级架构。 这项工作提出了方法，可重复地生产基于LLC的几何形状的纳米结构，使用的固有速度的光聚合允许控制基于纳米级几何形状的聚合物性能。如果能够实现这样的控制，则可以实现分离技术、水凝胶和组织工程等多种应用的实质性进展。一个普遍的主题将是学生教育。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拟议的研究，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向当地和农村高中化学课提出的模块的一部分向高中生介绍。