Effects of surfactants on the microstructures of electrospun polyacrylonitrile nanofibers and their carbonized analogs

Abstract

In this study, the influence of surfactants on the processability of electrospun polyacrylonitrile (PAN) nanofibers and their carbonized analogs was investigated. The surfactants employed in this effort are Triton X-100 (nonionic surfactant, SF-N), sodium dodecyl sulfate (SDS) (anionic surfactant, SF-A), and hexadecyltrimethylammonium bromide (HDTMAB) (cationic surfactant, SF-C). Interactions between electrospun PAN and the surfactants, reflected in effects on as-spun and carbonized nanofiber morphologies and microstructures, were explored. The results show that uniform nanofibers are obtained when cationic and anionic surfactants (surfactant free and nonionic surfactants) are utilized in the preparation of electrospun PAN. In contrast, a bead-on-a-string morphology results when the aniconic and cationic surfactants are present, and defect structure is enhanced with cationic surfactant addition. Moreover, fiber breakage is observed when the nonionic surfactant Triton X-100 is employed for electrospinning. After carbonizaition, the PAN polymers were observed to have less ordered structures with addition of any type of surfactant used for electrospinning and the disorder becomes more pronounced when the anionic surfactant is utilized. Owing to the fact that microstructure defects create midband gap states that enable more electrons to be emitted from the fiber, an enhancement of electron emission is observed for PAN electrospun in the presence of the anionic surfactant.