Properties and Applications of the β Phase Poly(vinylidene fluoride)

Abstract

Poly(vinylidene fluoride), PVDF, as one of important polymeric materials with extensively scientific interests and technological applications, shows five crystalline polymorphs with α, β, γ, δ and ε phases obtained by different processing methods. Among them, β phase PVDF presents outstanding electrical characteristics including piezo-, pyro-and ferroelectric properties. These electroactive properties are increasingly important in applications such as energy storage, spin valve devices, biomedicine, sensors and smart scaffolds. This article discusses the basic knowledge and character methods for PVDF fabrication and provides an overview of recent advances on the phase modification and recent applications of the β phase PVDF are reported. This study may provide an insight for the development and utilization for β phase PVDF nanofilms in future electronics.

Physico‐Chemical Characterizations of Poly(vinylidene fluoride)/Cu3(BTC)2 Composite Membranes Prepared by In Situ Crystal Growth

“…In fact, it has been recently accepted that bands at 445, 840 and 1,275 cm −1 , the later appearing as a shoulder, are attributed exclusively to the β ‐phase (Fig. a, green line) . These bands allow distinguishing between the β ‐ and γ ‐phases.…”

“…Figure a presents the results of the ATR‐FTIR for the PVDF membrane prepared under different conditions. ATR‐FTIR spectrum of pristine PVDF (black line) shows the characteristic bands of the α phase at 615, 765, 795, and 976 cm −1 . These bands disappeared in the spectrum of PVDF produced using DMSO and annealed at 90°C for 5 h. Moreover, new bands appear indicating the predominant presence of the β ‐phase.…”

Flexible Quasi‐Solid State Ionogels with Remarkable Seebeck Coefficient and High Thermoelectric Properties

“…This conclusion is supported by the fact that an aqueous solution of a salt like NaCl, KCl, or LiCl exhibits a small Seebeck coefficient of 0.5-0.8 mV K −1 . [42] The β phase of PVDF-HFP always appears in the ionogels with different EMIM:DCA loadings as shown in Figure 3b. For example, a Seebeck coefficient of 7 mV K −1 was observed on the dodecanol solution of TBAN (chemical structures of dedecanol and TBAN shown in Figure S8 in the Supporting Information) since dodecanol is less polar than water.…”

Recent Progress on Piezoelectric, Pyroelectric, and Magnetoelectric Polymer‐Based Energy‐Harvesting Devices

“…In particular, the homopolymer PVDF and its copolymer poly(vinylidene fluoride‐ co ‐trifluoroethylene) (P(VDF‐TrFE)) have been widely used for applications . PVDF and its copolymers show the best‐known electroactive properties among polymeric materials, thus being the choice of excellence for smart material applications in areas such as sensors, actuators, ultrasonic transducers, energy harvesters, biomaterials, and energy storage systems, among others. PVDF and P(VDF TrFE) show lower piezoelectric and pyroelectric coefficients than the piezoelectric ceramic lead zirconate titanate (PZT); nonetheless, they present the advantages of low permittivity and thermal conductivity, good impedance matching to air and water, flexibility, softness, processability, and relatively low cost [9b,10]…”