Thermally Treated Graphene Oxide/Polyacrylonitrile Based Electrospun Carbon Nanofiber Precursor

Abstract

Graphene oxide (GO) included polyacrylonitrile (PAN) composite electrospun nanofiber webs were fabricated, and thermal oxidation of PAN/GO composite nanofibers were performed at different temperatures (25, 250, 280, and 300 °C) for different time intervals (0, 1 and 3 h.) to investigate the oxidation process of PAN/GO nanofibers. The thermal oxidation process of PAN has a complex mechanism through the cyclization and dehydrogenation steps. For all oxidized samples, Electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared-Attenuated Total Reflectance (FTIR-ATR) Spectroscopic results were comparatively evaluated to investigate the effect of GO addition onto the nanofiber webs. After heat treatment, change in C1s spectra from virgin PAN to oxidized form was detected and sp2 carbon is developed. The presence of GO accelerated the oxidation and development of the final structure. At shorter heat treatment time, less oxidized forms are obtained. The cyclization of nitrile pendant groups of PAN forming polyimine type structure is the main reaction occurs during stabilization. In addition to the imine sequences with three to six units long, the presence of polar groups C═O, OH and COOH in the chains facilitates the initiation of the cyclization process through a nucleophilic attack and accelerates the subsequent oxidative ring closure reactions which these newly formed bonds during thermal oxidation and stabilization steps play an essential role on the carbonization process as an intermediate form of PAN based structures.

Nonflammable pre-carbonized polyacrylonitrile nanofiber webs

“…When EIS results (Fig. 7) were evaluated together with our previous studies [34,57], the linear chain form of the PAN changed as a partially cyclized structure with side groups, around 100 times lower charge transfer resistances were obtained compared to Graphene oxide containing oxidized PAN nanofibers indicating the formation of cyclized structure which will be disturbed by the presence of graphene oxide in the structure. The oxidized linear structure of PAN becomes more resistive with the increased oxidation temperature due to its newly occurred partially cyclized form, which surrounds with side groups.…”

The migration behavior of electrospun nanofibers within cotton slivers in roller drafting and their effects on composite yarn quality

“…PAN is a kind of polar polymer with good molecular chain flexibility, and PS is a kind of nonpolar polymer with molecular chain rigidity. [28][29][30] As shown in Figure 3(b-e), PAN electrospun fibers were ultrafine; their average diameter was around 225 nm. However, PS electrospun fibers were relatively thick and the average diameter was about 1118 nm.…”

Single Step Electrochemical Semi‐Exfoliated S‐Doped Graphene‐Like Structures from Commercial Carbon Fiber as Efficient Metal‐Free Catalyst for Hydrogen Evolution Reaction

“…[56] The peaks at about 1688 cm À 1 and 1595 cm À 1 were associated with the ketone group (C=O) and ChemElectroChem sp 2 hybridization of carbon, respectively. [57] A band at about 1417 cm À 1 reveals the CÀ O, and 1223 cm À 1 indicates the CÀ O stretching of epoxy groups. [58] Aromatic CÀ H bending peaks can be seen at 1891 cm À 1 and 1740 cm À 1, besides the peak at 1451 cm À 1 was attributed to aromatic skeleton stretching.…”