Size control of electrospun hydroxyapatite nanofibers by sol-gel system

This work reported the production of hydroxyapatite nanofibers by combining electrospinning and a sol-gel system in details. The fibers were electrospun from a mixture of the sol formed with Ca(NO3)2 x 4H2O/P2O5 in ethanol/ethylene glycol solution mixtures and the polyvinylpyrrolidone polymer, followed by a thermal treatment. The nanofibers were analyzed for their morphology (Scanning Electron Microscopy, SEM), chemical composition (Fourier Transform Infrared Spectroscopy, FTIR) and structure (X-ray diffraction, XRD) as well as thermal properties (Differential scanning calorimetric, DSC and thermogravimetric, TG). The results indicated that the sol was distributed uniformly in the PVP fibers. After calcinations at 600 degrees C for 3 h, the pure HAP phase could be obtained, and the smooth as-electrospun fibers shrunk and the fiber diameter decreased because of the removal of the polymer. Based on the systematic parametric study, it was possible to control the diameter ranging from 400 to 900 nm and morphology of the electrospun polymer fibers. Moreover, thses HAP nanofibers were flexible as cotton and the fibers mat would not rupture even folding it on a paper. So the good flexibility and high mechanical properties might favor their application in the future.