Correlation of annealing temperature, morphology, and electro-mechanical properties of electrospun piezoelectric nanofibers

Piezoelectric polymeric nanofibers, such as P(VDF-TrFE), are promising nanostructures for sensing/actuation applications where flexibility of the component is required, for example soft robotics, conformal sensors, and energy harvesting devices. A challenge in polymeric piezoelectric materials is that their electromechanical coupling efficiency must be improved to approach that of bulk piezo ceramics. The electromechanical coupling factor is proportional to Yd(2) (where Y is the elastic modulus, and d is the piezoelectric constant); therefore, the investigation of inter-dependence of these properties as function of thermal annealing is important. Although effect of thermal annealing on thin film of PVDF has been studied, however, detailed investigations of correlation of annealing temperature, morphology, and electro-mechanical properties of electrospun piezoelectric nanofibers have not been reported, in particular at single nanofiber level. We report on the effect of various annealing temperatures on mechanical and piezoelectric properties at the single nanofiber level using nanoindentation and piezoresponse force microscopy (PFM). FTIR, XRD, and WAXD spectroscopies were also employed to quantitatively and qualitatively explain the enhancement of these properties. (C) 2017 Elsevier Ltd. All rights reserved.