RUI: Continuous Processing for Improved Properties of Nanofibers

静电纺丝是一种多用途且经济的纳米技术，用于制造纳米级直径的聚合物纤维。聚合物纳米纤维可用于生产轻质复合材料、纳米电子、高效能量存储和转换设备、高响应传感器和生物医学设备，它们的小尺寸提高了性能。理论上，纳米材料有望在机械强度、电导率和传感等方面优于传统材料。然而，在实际应用中，即使在调整尺寸效应后，电纺纳米纤维也比较大的传统纤维弱得多。该奖项支持对一种新的制造工艺的基础研究，该工艺在制造过程中拉伸柔韧的静电纺丝纳米纤维，其方式与传统纤维制造中使用的拉伸工艺相同，并且已知该工艺可提高大规模纤维的机械强度和功能特性。新方法的主要优点是它可以作为连续静电纺丝工艺的附加阶段实施，并且适合于大规模生产。这项工作将支持创新纳米纤维材料在各种技术和行业中的应用。该项目的执行将涉及研究生和本科生的研究人员，他们将获得纳米技术的第一手经验。代表性不足的K-12学生将通过各种外展活动接触到该项目。在静电纺丝纳米纤维中观察到的较差的大分子取向和力学性能是由于残余溶剂存在下的链松弛造成的。由于缺乏对纤维组织和操作的控制，研究和克服这一挑战的策略受到限制，这妨碍了基本的纤维加工技术，如后拉伸。这项工作将利用平行的自动化轨道同时固定和拉伸数千个单独的纳米纤维。在溶剂完全蒸发之前，纳米纤维可以在收集后立即以半固体状态湿拉伸。系统地研究了几种不同的聚合物、蛋白质和碳材料的加工参数，如总伸长率、伸长率和溶剂蒸发率，以确定它们与最终纳米纤维分子和功能特性的关系。纳米纤维直径对湿拉伸机理的影响将为分子约束等独特的纳米效应提供新的见解。

Electrospinning is a versatile and economical nanotechnology used to fabricate polymer fibers with nanoscale diameters. Polymer nanofibers can be used to produce lightweight composite materials, nanoelectronics, efficient energy storage and conversion devices, highly responsive sensors, and biomedical devices where their small dimension enhances performance. Nanomaterials are theoretically expected to outperform conventional materials in categories such as mechanical strength, conductivity, and sensing. However, in practice, electrospun nanofibers are much weaker than larger conventional fibers even when adjusting for the size effect. This award supports fundamental research into a new manufacturing process that stretches pliable electrospun nanofibers during manufacture in the same way as the drawing process that is used in conventional fiber manufacturing and that is known to enhance the mechanical strength and functional properties of larger-scale fibers. The key advantage of the new method is that it can be implemented as an additional stage in the continuous electrospinning process and is amenable to full scale production. This work will support the advancement of innovative nanofiber materials for application in a wide variety of technologies and industries. Execution of this project will involve graduate and undergraduate researchers who will gain firsthand experience in nanotechnology. Underrepresented K-12 students will be exposed to the project through various outreach activities. It has been hypothesized that the poor macromolecular alignment and mechanical properties observed in electrospun nanofibers is due to chain relaxation in the presence of residual solvent. Strategies to investigate and overcome this challenge have been limited by an overall lack of control over fiber organization and manipulation that preclude fundamental fiber processing techniques such as post-stretching. This work will utilize parallel automated tracks to simultaneously immobilize and stretch thousands of individual nanofibers. Nanofibers can be wet-stretched in the semi-solid state immediately upon collection before solvent has fully evaporated. A systematic investigation of processing parameters such as total elongation, rate of elongation, and solvent evaporation rate will be conducted for several different polymers, proteins and carbon materials to determine their relationship to final nanofiber molecular and functional properties. The influence of nanofiber diameter on the mechanisms of wet-stretching will offer new insights into unique nanoscale effects such as molecular confinement.