Tuning mechanical properties of electrospun piezoelectric nanofibers by heat treatment

We report an annealing method which significantly enhances the piezoelectric performance by simultaneously tuning morphology and crystalline phase of electrospun P(VDF-TrFE) nanofibers. Annealing process-induced transformation, from α to β crystalline phase at lattice scale, also changes fiber morphology at micrometer scale. The underlying differences between as-spun and annealed P(VDF-TrFE) nanofibers for their stretch-hold deformation were examined via in-situ synchrotron for both small and wide angle X-ray scattering (SAXS and WAXS). Transmission X-ray microscopy (TXM) characterization reveals the underneath fiber orientation subjected to different levels of deformation. Multi-length scale microstructural evolution demonstrates distinct deformation behaviors of the as-spun and annealed nanofibers during uniaxial tensile loading. The findings can be applied for multi-scale structure modulation for the design of future piezoelectric devices.