Highly porous polyacrylonitrile/polystyrene nanofibers by electrospinning

The concept of phase separation was coupled with electrospinning to induce polyacrylonitrile (PAN) and polystyrene (PS) bicomponent electrospun fibers that, upon removal of the phase-separated PS domains by solvent extraction, became nanoporous. Electrospinning of PAN (Mw 150 kDa) with 5 % w/w PS (Mw 250 kDa) at a 10 % w/w total concentration in N,N-dimethylformamide (DMF) produced fibers with stable morphology and average diameters from 1130±680 to 890±340 nm by FESEM. The nanoporous fibers made from a 95/5 w/w PAN/PS bicomponent precursor had internal pores of about 20∼110 nanometers. Pore sizes of the porous PAN fibers were decreased to approximately ∼25 nm after oxidation and carbonization thermal treatment because of fiber shrinkage during the thermal treatment. The fibers retained a high density of pores after the thermal treatment.