Piezoelectric performance of aligned PVDF nanofibers fabricated by electrospinning and mechanical spinning

Considerable attention has been paid to aligned polymer nanofibers because of their appealing mechanical and piezoelectric properties. With modified electrospinning, the aligned poly (vinylidene fluoride) (PVDF) nanofibers can be produced. However, the roles of mechanical stretching and electrical poling during this process require further investigation. Here, we utilize a rotary drum to collect the fibers by both electrospinning and mechanical drawing approaches. The fiber mats were characterized by Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectrometer (FTIR) and X-Ray Diffraction (XRD), and were directly made into sensing films without post electric poling treatment. Their piezoelectricity was measured in our home-made dynamic air pressure sensor. Results show that the β-phase predominates in both electrospun and mechanically-spun nanofibers. However, sensor based on electrospun β-PVDF fiber mat presented a sensitivity of 178 mV/kPa, while only a very weak output signal was observed in the mechanically spun β-PVDF fiber mat. Therefore, mechanical stretching and electrical poling may play key roles in inducing the β-phase and orienting the dipoles in a preferential direction during electrospinning process, respectively.