Collaborative Research: Understanding and Controlling the Mechanical and Thermal Properties of Polymer Nanofibers

聚合物在现代文明中的应用无处不在。 然而，聚合物通常被认为是不良的热导体，而许多应用将受益于能够用作良好热导体的聚合物材料。 最近的研究表明，经过显著拉伸的聚合物材料可以大大增强机械强度和热传导。 因此，我们的目标是研究在射流中形成的纳米纤维的机械和热性能，诱导显着的拉伸。 我们预计，与相同聚合物的较大的未拉伸版本相比，这些纳米纤维中的热传输可能会大大增强。 我们将研究射流如何拉伸聚合物分子，以及由此产生的分子取向如何反过来导致增强的机械强度和热传导，这最终可能导致令人兴奋的新聚合物材料，这些材料非常坚固，灵活，并且是热的良好导体。 这些材料将能够实现各种应用，例如柔性电子产品和显示器，太阳能电池以及与高功率电子产品集成的先进结构材料，从而导致未来的重大技术进步。 该项目整合了研究和教育部分，在跨学科环境中培养研究生，并通过范德比尔特和菲斯克大学之间的合作将影响扩大到代表性不足的少数民族。该项目旨在将电纺聚合物纳米纤维的制造工艺条件、结构以及机械和热性能联系起来。 该方法是整合电纺过程的知情控制，机械和热传输性能测量，彻底的微观结构表征和理论分析，以深入了解电纺参数如何影响微结构，机械和热性能。 结构和性能表征将在单个纤维水平上进行，从而避免对潜在的纤维异质性进行平均。 微结构将使用显微拉曼光谱进行表征，该技术能够从少量样品中提供有关分子组成和取向的详细信息。 将使用原子力显微镜进行3点弯曲测试来表征各个纳米纤维的机械性能。 单个纳米纤维的热性能将使用定制的微型设备进行测量。 通过了解静电纺丝参数如何影响微观结构，以及微观结构与机械/热性能之间的相互作用，我们将能够优化沉积参数，以获得具有可调机械和热性能的聚合物材料。

Polymers find ubiquitous applications in modern civilization. However, polymers are generally regarded as poor heat conductors, while many applications would benefit from polymer materials that are able to function as good heat conductors. Recent studies have suggested polymer materials that have been significantly stretched could have substantially enhanced mechanical strength and heat conduction. We therefore aim to study the mechanical and thermal properties of nanoscale fibers formed in a jet that induces significant stretching. We expect that heat transport in these nanofibers may be profoundly enhanced compared to larger, unstretched versions of the same polymer. We will study how the jet stretches the polymer molecules, and how the resulting molecular orientation in turn results in enhanced mechanical strength and heat conduction, which may eventually lead to exciting new polymer materials that are extremely strong, flexible, and good conductors of heat. Such materials would enable a variety of applications, such as flexible electronics and displays, solar cells, and advanced structural materials integrated with high-power electronics, leading to significant future technological advancements. The project has integrated research and educational components to train graduate students in an interdisciplinary environment, and to extend the impact to underrepresented minorities through collaboration between Vanderbilt and Fisk universities.This project aims to correlate the manufacturing process conditions, structure, as well as mechanical and thermal properties of electrospun polymer nanofibers. The approach is to integrate informed control of the electrospinning process, mechanical and thermal transport property measurement, thorough microstructural characterization, and theoretical analysis to achieve an in-depth understanding of how electrospinning parameters affect nanofiber microstructure, mechanical and thermal properties. The structure and property characterization will be performed at an individual nanofiber level, thereby avoiding averaging over potential fiber heterogeneity. Microstructure will be characterized using micro-Raman spectroscopy, a technique which is able to provide detailed information about molecular composition and orientation from a small sample volume. Mechanical properties of individual nanofibers will be characterized using an atomic force microscope to perform a 3-point bend test. Thermal properties of individual nanofibers will be measured using custom-built microdevices. With an understanding of how electrospinning parameters affect microstructure, and the interplay between microstructure and mechanical/thermal properties, we will be able to optimize deposition parameters to achieve polymeric materials with tunable mechanical and thermal properties.