Comparative Study of Metal Substrates for Improved Carbonization of Electrospun PAN Nanofibers

Abstract

Carbon nanofibers are used for a broad range of applications, from nano-composites to energy storage devices. They are typically produced from electrospun poly(acrylonitrile) nanofibers by thermal stabilization and carbonization. The nanofiber mats are usually placed freely movable in an oven, which leads to relaxation of internal stress within the nanofibers, making them thicker and shorter. To preserve their pristine morphology they can be mechanically fixated, which may cause the nanofibers to break. In a previous study, we demonstrated that sandwiching the nanofiber mats between metal sheets retained their morphology during stabilization and incipient carbonization at 500 °C. Here, we present a comparative study of stainless steel, titanium, copper and silicon substrate sandwiches at carbonization temperatures of 500 °C, 800 °C and 1200 °C. Helium ion microscopy revealed that all metals mostly eliminated nanofiber deformation, whereas silicone achieved the best results in this regard. The highest temperatures for which the metals were shown to be applicable were 500 °C for silicon, 800 °C for stainless steel and copper, and 1200 °C for titanium. Fourier transform infrared and Raman spectroscopy revealed a higher degree of carbonization and increased crystallinity for higher temperatures, which was shown to depend on the substrate material.

Effects of Incorporating Titanium Dioxide with Titanium Carbide on Hybrid Materials Reinforced with Polyaniline: Synthesis, Characterization, Electrochemical and Supercapacitive Properties

“…Different nanostructured electrode materials for supercapacitors based on different dimensions ranging from zero to three such as activated carbon, nanorods, nanowires, nanotubes and nanofibers are known [5][6][7]. Recently, electrode materials based on carbon nanofibers, which are prepared by electrospinning technique with subsequent carbonization, are also considered as promising electrode materials for supercapacitors due to their high electrical conductivity and their specific surface area and porosity [8][9][10][11].…”

Optical Properties of Electrospun Nanofiber Mats

“…Electrospinning can be used to produce very fine fibers, typically in the range of some ten to some hundred micrometers, from a polymer solution or melt [1][2][3]. Usually, a syringe with a fine needle or a polymer-coated wire or rotating drum enable introducing the polymer solution into a strong electric field, which forces the polymer droplets to fly from the high-voltage electrode to the grounded collector [4][5][6], while several other techniques are also available and enable faster spinning, or producing special fibers, such as core-shell fibers [7][8][9]. The nanofibers deposited on the collector are usually arbitrarily oriented, but different techniques such as a fast-rotating collector or introduction of conductive or dielectric areas in the collector can be used to gain a certain amount of orientation of the fibers [10][11][12].…”

Nanofibers are a matter of perspective: effects of methodology and subjectivity on diameter measurements

“…Helium ion microscopy (HIM) is in many regards similar to SEM, however, hitherto much less established and accessible. It has already been used in several studies to image nanobers 8,15,16 and it is of particular interest for diameter measurements due to its capacity to image insulating samples without prior coating. 17 Atomic force microscopy (AFM) is oen used to characterize nanober properties beyond mere morphology, such as magnetization, friction, or mechanical strength.…”