FABRICATION OF FLEXIBLE POLYACRYLONITRILE/ZINC OXIDE CO-AXIAL NANOFIBERS WITH PHOTOCATALYTIC ACTIVITY BY ELECTROSPINNING

Polyacrylonitrile (PAN)/zinc oxide (ZnO) nanofibers were fabricated in flexible core/sheath structure using combination of sol-gel and co-axial electrospinning techniques. PAN dissolved in dimethyl formamide (DMF) was used as core-solution while poly vinyl pyrrolidone (PVP) solution containing ZnO sol in DMF was used as sheath-solution. Concentration of PAN in the core-solution was varied in the range of 8 to 12 wt%, while the PVP concentration in the sheath-solution was varied in the range of 8 to 18 wt%. Under the applied potential of 25 kV/cm, the uniform and bead-free co-axial nanofibers can be fabricated. Upon the calcination, at temperature in the range of 300-500oC, PVP in the sheath is removed while ZnO sol is crystallized into ZnO nanoparticles attached to the PAN core. The presence of PAN core, which can withstand the calcination, provides flexibility for the final PAN/ZnO nanofibers so that crumbling of the fibers during the use can be avoided. The calcined fibers have average diameter of 210-1,400 nm and 21-39 nm in crystalline size of ZnO. The activity of PAN/ZnO nanofibers on the photocatalytic degradation of methylene blue is almost the same as that of ZnO nanoparticles. Furthermore, the effects of calcination temperature, calcination time, and aging time of ZnO sol on the photocatalytic activity were studied.