Melt Electrowriting of Electroactive Poly(vinylidene difluoride) Fibers
Poly(vinylidene difluoride) (PVDF) has piezoelectric properties suitable for numerous applications such as flexible electronics, sensing and biomedical materials. In this study, individual fibers with diameters ranging from 17-55 μm were processed using melt electrowriting (MEW). Electroactive PVDF fibers can be fabricated via MEW, while the polymer could remain molten for up to ten hours without noticeable changes in the resulting fiber diameter. MEW processing parameters for PVDF were investigated, including applied voltage, pressure and temperature. A rapid fiber characterization methodology for MEW that automatically determines the fiber diameters from camera images taken of microscope slides was developed and validated. The outputs from this approach followed previous MEW processing trends already identified with different polymers, although overestimation of the < 25 micron fiber diameters was observed. The transformation of the PVDF crystalline phase to the electroactive beta-phase – without poling – was confirmed using piezo-force microscopy and revealed that the PVDF fibers possess piezoelectric responses showing d33~19 pm/V.