Hierarchically Structured Porous Piezoelectric Polymer Nanofibers for Energy Harvesting

Abstract

Hierarchically porous piezoelectric polymer nanofibers are prepared through precise control over the thermodynamics and kinetics of liquid–liquid phase separation of nonsolvent (water) in poly(vinylidene fluoride‐trifluoroethylene) (P(VDF‐TrFE)) solution. Hierarchy is achieved by fabricating fibers with pores only on the surface of the fiber, or pores only inside the fiber with a closed surface, or pores that are homogeneously distributed in both the volume and surface of the nanofiber. For the fabrication of hierarchically porous nanofibers, guidelines are formulated. A detailed experimental and simulation study of the influence of different porosities on the electrical output of piezoelectric nanogenerators is presented. It is shown that bulk porosity significantly increases the power output of the comprising nanogenerator, whereas surface porosity deteriorates electrical performance. Finite element method simulations attribute the better performance to increased volumetric strain in bulk porous nanofibers.

Flexible electrospun PVDF–BaTiO3 hybrid structure pressure sensor with enhanced efficiency

“…An increment in bulk porosity leads to reduction of relative permittivity and enhancement in deformability of nanobers which result in increasing the output of the sample. 39 The gold sputtered conguration almost shows a frequency independent performance as the sensitivity stays the same in different frequencies. The continuously sprayed nanocomposite provides a weak sensitivity in lower frequencies.…”

Self‐Poled Sausage‐Like PVDF Nanowires Produced by Confined Phase Inversion as Novel Piezoelectric Nanogenerators

“…The depend ence of the typical domain or droplet size on the pore radius is in qualitative agreement with the experimental observa tions: wider pores produce a larger structure size, in principle in agreement with Rayleigh instability theory. [43] Interestingly, the same trend in the droplet size is observed when increasing the mean polymer concentration, while keeping the pore radius constant.…”

“…As is wellknown, due to the strong repulsive interaction between the polymer and water, PVDF/DMF or, equivalently, P(VDFTrFE)/DMF, solutions undergo rapid liquidliquid demixing upon quenching in water [21,42,43] either by exposure to a wet atmosphere or submersion into a water bath. For this reason, this system lends itself so well for functional manufacture based on such "nonsolventinduced phase separation" (NIPS) or "phase inversion", of which microporous membranes perhaps present the best known application.…”

“…The latter have been evaluated in previous work. [43,50] We assume a simple surface free energy of the form:…”

Ultrasound‐Powered Implants: A Critical Review of Piezoelectric Material Selection and Applications

“…Finally, porosity can also be incorporated into film structures to enhance the piezoelectric properties (Figure 3C5). [ 220 ]…”