CAREER: Multi-Functional Particle Assemblies in Polymer Nanocomposites

技术概述：在这个CAREER项目中，PI将设计多功能聚合物复合材料，展示具有可调机械和电气性能的自组装纳米结构。该项目旨在构建平衡磁性纳米结构，使其多功能性能随分子间力的变化而变化和优化。聚合物修饰的氧化铁纳米颗粒是一个全面的模型系统，提供各向异性和各向同性相互作用，可以通过颗粒大小、颗粒功能（例如接枝链、离子或生物配体的长度和密度）和外部磁场进行调节。本研究计划将通过非线性流变学、散射和显微技术解释各种相互作用的作用，阐明热力学平衡自组装结构的形成。PI建议研究三维结构的自组装机制的基本原理及其新的可逆自组装行为。聚合物链的构象熵在组装机制中的作用也将被研究。此外，还将研究不同粒径颗粒混合物的相图，以获得比单峰粒径颗粒更复杂的新结构。团簇组织动力学和从无序结构到有序结构的转变将被原位测量，以支持平衡状态的稳定性和复杂结构的可逆性。非技术概述：该研究将提供一种有前途的简单合成和加工方法来制造多功能纳米材料，该材料可用于需要增强机械和电气性能的应用。这个CAREER项目将为磁性纳米粒子的自组装开辟新的途径，它可以应用于具有可调性能的自修复膜和复合材料。该研究结果将对新型聚合物复合材料的设计产生影响，因为它们的行为类似于智能材料，例如对pH和温度敏感的刺激响应共聚物，或者电导率和转导性能随颗粒排列而变化的材料。此外，可逆自组装概念在生物相容性材料、机械传感器、高增强化合物和新型高能材料方面具有潜在的应用前景。基本的纳米级相互作用及其对柔性聚合物纳米复合材料的中尺度性能（例如，在一种材料中结合机械和导电性能）的影响将被探索。在这个项目的过程中，PI计划通过在她的实验室提供研究经验来教育和培训高中科学教师，以开发一个高中科学课程的合作科学项目。为了培养未被充分代表的学生对科学、研究和工程的兴趣，她将与女工程师协会合作，并在其本地和区域会议和外展活动中传播她的研究成果。该PI将把她的研究活动融入到高分子科学的教学中，并积极吸引本科生参与研究。

TECHNICAL SUMMARY:The PI will design multi-functional polymer composites displaying self-assembled nanostructures with tunable mechanical and electrical properties in this CAREER project. The project aims to construct equilibrium magnetic nanostructures in which their multi-functional properties can be varied and optimized with the intermolecular forces. Polymer decorated iron oxide nanoparticles are a comprehensive model system offering both anisotropic and isotropic interactions that can be tuned with particle size, particle functionality (e.g. length and density of grafted chains, ions or bioligands) and external magnetic fields. This research plan will explain the role of various interactions and elucidate the formation of thermodynamically equilibrium self-assembled structures through non-linear rheology, scattering and microscopy. The PI proposes to investigate the fundamentals of the self-assembly mechanism for three-dimensional structures and their novel reversible self-assembly behavior. The role of conformational entropy of polymer chains on the assembly mechanism will be also examined. In addition, the phase diagram for a mixture of particles with different sizes will be studied to achieve complex novel structures other than obtained from monomodal particle sizes. Cluster organization kinetics and transition from disordered to ordered structures will be measured in-situ to underpin the stability of equilibrium states and reversibility of complex architectures.NON-TECHNICAL SUMMARY:The proposed research will offer a promising and simple synthesis and processing method to make multi-functional nanomaterials which can be used for applications requiring enhanced mechanical and electrical properties. This CAREER project will open new routes to the self-assembly of magnetic nanoparticles which can be applied to self-healing membranes and composites with tunable properties. The results will have an impact on design of new polymeric composites as they behave akin to smart materials, such as stimuli-responsive copolymers sensitive to pH and temperature or materials in which the conductivity and transduction properties change with the arrangement of particles. Moreover, the reversible self-assembly concept will have potential applications in biocompatible materials, mechanical sensors, highly reinforced compounds and new energetic materials. The fundamental nanoscale interactions and their impact on the mesoscale properties (e.g. combined mechanical and conductive properties in one material) of flexible polymer nanocomposites will be explored. Within the course of this project, the PI plans to educate and train high school science teachers by offering research experiences in her laboratory to develop a collaborative science project for high school science curricula. To foster the interest of underrepresented students in science, research and engineering, she will work with the Society of Women Engineers and disseminate her research findings in their local and regional meetings and outreach activities. The PI will integrate her research activities into teaching of polymer science and will also actively engage undergraduate students in research.