Preparation of porous hollow polyacrylonitrile ultrafine fibers by coaxial electrospinning

To obtain a kind of desired porous hollow fibers,with ployacrylonitrile(PAN)/polyvinyl pyrrolidone(PVP)/N,N-dimethylformamide(DMF) mixture solution as sheath spinning solution,and PVP/DMF,polyoxyethylene(PEO)/DMF and PVP/ethanol(EtOH) as core spinning solution respectively,composite ultrafine fibers were prepared by coaxial electrospinning.The water-soluble polymers in the composite ultrafine fibers were removed by deionized water ultrasonic vibration.The obtained ultrafine fibers were characterized by field emission scanning electron microscopy(FESEM).The FESEM observation revealed that the hollow ultrafine fibers had inadequate pores when PVP/DMF solution was used as the core spinning solution;the ultrafine fibers displayed compact porous structure when PEO/DMF solution was used;and porous hollow PAN ultrafine fibers could be fabricated only when PVP/EtOH solution was used.