RUI: Continuous Processing for Improved Properties of Nanofibers

Rowan University, Glassboro NJ

Investigators

Abstract

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.