A Comprehensive Review of Piezoelectric PVDF Polymer Fabrications and Characteristics

Abstract

Polyvinylidene fluoride (PVDF) polymer films, renowned for their exceptional piezoelectric, pyroelectric, and ferroelectric properties, offer a versatile platform for the development of cutting-edge micro-scale functional devices, enabling innovative applications ranging from energy harvesting and sensing to medical diagnostics and actuation. This paper presents an in-depth review of the material properties, fabrication methodologies, and characterization of PVDF films. Initially, a comprehensive description of the physical, mechanical, chemical, thermal, electrical, and electromechanical properties is provided. The unique combination of piezoelectric, pyroelectric, and ferroelectric properties, coupled with its excellent chemical resistance and mechanical strength, makes PVDF a highly valuable material for a wide range of applications. Subsequently, the fabrication techniques, phase transitions and their achievement methods, and copolymerization and composites employed to improve and optimize the PVDF properties were elaborated. Enhancing the phase transition in PVDF films, especially promoting the high-performance β-phase, can be achieved through various processing techniques, leading to significantly enhanced piezoelectric and pyroelectric properties, which are essential for diverse applications. This concludes the discussion of PVDF material characterization and its associated techniques for thermal, crystal structure, mechanical, electrical, ferroelectric, piezoelectric, electromechanical, and pyroelectric properties, which provide crucial insights into the material properties of PVDF films, directly impacting their performance in applications. By understanding these aspects, researchers and engineers can gain valuable insights into optimizing PVDF-based devices for various applications, including energy-harvesting, sensing, and biomedical devices, thereby driving advancements in these fields.

Keywords: characterizations; fabrication; material properties; piezoelectric; poly(vinylidene fluoride).

Figure 1

Different properties of PVDF.

Figure 2

Different phases of PVDF and their properties. (a) α-phase, (b) β-phase, and (c) γ-phase. Redrawn from reference [11,74].

Figure 3

Different methods of improving PVDF properties.

Figure 4

A 3D printing mechanism for PVDF films.

Figure 5

The PVDF polymer’s crystalline phase transformation diagram [140].

Figure 6

Phase transition by temperature stretching method. The 1D WAXS profiles during stretching at (A) 60 °C and (B) 140 °C [142].

Figure 7

Diagrammatic representation of PVDF films’ uniaxial stretching process and structure formation phase change, crystalline orientation, and crystalline shape as the stretch ratio increases [145].

Figure 8

Various stretching conditions of PVDF films for structure evolution. (a₁) FTIR spectra. (a₂) PVDF films’ phase composition changes when the stretch ratio rises. (b₁) DSC traces. (b₂) Crystallinity and melting temperatures in relation to stretch ratios. (c₁) The 1D WAXD patterns. (c₂) The (110)/(200)β-phase’s crystallite size and 2θ as a function of stretch ratio, determined by 1D XRD [145].

Figure 9

Experimental setup for biaxial stretching of PVDF [104].

Figure 10

Test setup for measurement of piezoelectric coefficient: (a) d₃₃ and (b) d₃₁ [104].

Figure 11

FTIR spectra of stretched PVDF: (a) uniaxial and (b–d) biaxial [104].

Figure 12

Schematic diagram of in situ polarization for PVDF film [156].

Figure 13

Piezoelectric coefficient corresponding to different polarization voltage [156].

Figure 14

XRD patterns of PVDF-TrFE films after poling [9].

Figure 15

Schematic of setup for stretching and corona poling experiment [157].

Figure 16

(a) XRD patterns of PVDF after corona polarization. (b) FTIR spectra of PVDF [157].

Figure 17

PVDF copolymers: (a) poly(vinylidene fluoride-hexafluoropropylene), (b) poly(vinylidene fluoride-co-trifluoroethylene), and (c) poly(vinylidene fluoride-co-chlorotrifluoroethylene).

Figure 18

Effects of various nanofillers on PVDF properties and their applications.

Figure 19

The classification of thermoplastics blending criteria [189].

Figure 20

Different methods used for PVDF characterization. (a) Crystalline and amorphous regions measured with DSC. (b) Crystallin phases, measured with FTIR, XRD, and Raman. (c) Net polarization P-E hysteresis measured with a ferroelectric test station [204].

Figure 21

PVDF’s engineering stress–strain curves at various temperatures under uniaxial tensile deformation [142].

Figure 22

Yield stress and yield strain at various temperatures [142].

Figure 23

Structural characterizations by WAXD and FTIR. (a) BOPVDF films at room temperature are profiled using 1D WAXD. (b) The FTIR spectra analysis for the poled and fresh BOPVDF films in the transmission mode [205].

Figure 24

Tensile stress versus tensile strain curves of specimens printed with various crystalline patterns by using (a) PVDF-homopolymer and (b) PVDF-copolymer [208].

Figure 25

Tensile test for highly poled PVDF film. (a) The compression modulus (Y3) is obtained by nanoindentation. (b) Tensile moduli (Y1 and Y2) are obtained from the stress–strain curves [205].

Figure 26

The elastic modulus for both stretched and unstretched materials as a function of temperature. The data recorded at 1 and 10 Hz are represented by the dots and solid lines, respectively [209].

Figure 27

Dielectric constant for various temperature of PVDF-TrFE-CFE [57].

Figure 28

P-E loop for commercial piezoelectric PVDF polymer provided by PolyK Technologies [57].

Figure 29

Several piezoelectric coefficients for highly poled BOPVDF film: (a) d₃₃ and (b) d₃₁ and d₃₂ as a function of dynamic stress [205]. The red star in (a) indicates the d₃₃ value measured by the d₃₃ piezo meter with a static force of 2.5 N.

Figure 30

Pure PVDF piezoelectric film’s transverse strain at room temperature under various electric fields of 1 Hz [216].

Figure 31

Frequency dependence of the transverse strain caused by an electric field in a PVDF piezoelectric film [216].

Figure 32

Load effect on the electric field induced transverse strain response measured for PVDF-TrFE copolymer film. (a) Strain response as function of electric field for films under different loads. (b) Strain response and static load for films at various electric field strengths [216].

Figure 33

The impedance as a function of frequency: (a) the capacitance and (b) the dielectric loss [217].

Figure 34

Electromechanical coupling coefficient vs. dc-bias fields for the copolymer [217].

Figure 35

The pyroelectricities of PVDF film with various wt% GO-doping [122].

Figure 36

The pyroelectric currents of PVDF film with various wt% GO-doping [122].