Preparation of aligned polyimide-based carbon nanofibers by electrospinning

Abstract

Polyimide( PI) is a good carbon precursor owing to its high carbon yield and easy graphitization. PI nanofibers prepared by electrospinning were carbonized and graphitized to prepare aligned carbon nanofibers. Pyromelliticdianhydride and 4,4'- diaminodiphenyl ether were dissolved in N,N- dimethylacetamide at room temperature and stirred for 2 h to obtain a polyamide acid( PAA) solution,which was electrospun into aligned PAA nanofibers at 20 k V and collected by a rolling cylinder 18 cm belowthe needle with a rolling speed of 2 800 r / min. The PAA nanofibers were first imidized into the PI nanofibers at 350 ℃,then carbonized at 900 ℃ at a heating rate of 5 ℃ / min and finally graphitized at 3 000 ℃ to obtain continuous and aligned polyimide- based carbon nanofibers. The PAA solution with a concentration of 20% was the most suitable for electrospinning. SEMcharacterization shows that the average diameter of the carbon nanofibers is around 100 nm. The carbon nanofibers after graphitization at 3 000 ℃have a typical graphite structure.