Preparation of aligned polyimide-based carbon nanofibers by electrospinning

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 kV and collected by a rolling cylinder 18 cm below the 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. SEM characterization 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.