RUI: Continuous Processing for Improved Properties of Nanofibers

静电纺丝是一种用途广泛且经济的纳米技术，用于制备纳米直径的聚合物纤维。聚合物纳米纤维可用于制造轻质复合材料、纳米电子器件、高效能量存储和转换设备、高响应性传感器和生物医学设备，这些设备的小尺寸增强了性能。理论上，纳米材料有望在机械强度、导电性和传感等方面超过传统材料。然而，在实践中，即使考虑到尺寸效应，电纺纳米纤维也比更大的传统纤维弱得多。该奖项支持对一种新制造工艺的基础研究，该工艺在制造过程中以与传统纤维制造中使用的拉伸工艺相同的方式拉伸柔韧的电纺纳米纤维，并已知该工艺可以提高较大尺寸纤维的机械强度和功能特性。这种新方法的主要优点是，它可以作为连续电纺过程中的一个附加阶段来实施，并且适合大规模生产。这项工作将支持创新纳米纤维材料在广泛的技术和行业中应用的进步。该项目的实施将涉及研究生和本科生研究人员，他们将获得纳米技术方面的第一手经验。代表不足的K-12学生将通过各种外联活动接触到该项目。有人假设，电纺纳米纤维的大分子取向和力学性能较差是由于残留溶剂存在时的链松弛所致。研究和克服这一挑战的战略一直受到对纤维组织和操纵的全面缺乏控制的限制，这排除了后拉伸等基本纤维加工技术。这项工作将利用平行的自动轨道来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在半固体状态下湿拉伸。将对几种不同的聚合物、蛋白质和碳材料的工艺参数进行系统的研究，如总伸长率、伸长率和溶剂挥发率，以确定它们与最终的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制的影响将为分子限制等独特的纳米尺度效应提供新的见解。

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.