Strengthening of electromechanical properties for poly(vinylidene fluoride‐trifluoroethylene) films under tailored electric cycling

Abstract

Copolymers of polyvinylidene fluoride and trifluorethylene [P(VDF‐TrFE)] have potential applications in wearable and implantable electromechanical devices since they are mechanically flexible, and biocompatible. A tailored electric cyclic process is employed to enhance both electrical and mechanical properties in P(VDF‐TrFE) 65/35 mol % copolymer films. The films are subjected to lower and higher field magnitude electric cycling successively. For electrical properties, enhancement in remnant polarization, dielectric and piezoelectric constants occurs. From mechanical point of view, strengthening in the fracture strength happens. Wide‐angle X‐ray diffraction techniques examine changes of the orientation of the molecular chains, grain size, and crystallinity after electric cycling for the copolymer films. Scanning electron microscopy reveals evolutions of the microstructure, including rod‐like textures and fractography of the films. The results indicate that electric cycling causes the molecular chains to orient gradually along the direction perpendicular to the applied electric field. Consequently, an enhancement of 12.2% and 45% is realized for the remnant polarization and fracture strength, respectively for P(VDF‐TrFE) 65/35 copolymer film. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45926.

Fluorinated Polymers as Smart Materials for Advanced Biomedical Applications

“…As a result, different methodologies are available to produce materials into different designs and morphologies in order to meet specific requirements of applications that can vary from drug delivery [ 134 ], tissue engineering [ 135 , 136 ], sensors and actuators [ 77 , 137 ], medical device instrumentation [ 138 ], microfluidic systems [ 139 ], membranes for filtration and environmental engineering [ 140 , 141 ] and energy harvesting [ 39 ], among others. Thus, depending on the processing method, PVDF-based materials in the electroactive β-phase can be obtained in the form of films [ 75 , 142 ], porous films [ 143 , 144 , 145 ], fibres [ 136 ] and microspheres [ 146 ] ( Table 3 ).…”

Significantly Enhanced Electromechanical Performance of PDMS Crosslinked PVDF Hybrids

“…Poly(vinylidene fluoride) (PVDF)-based fluoropolymers have been well studied as electrostrictive EAPs for their ferroelectric properties and multiple crystalline morphologies, which results in a tunable ε r ranging from 10 to 100, along with rather high breakdown strength ( E b ) (100~300 MV/m). Meanwhile, their excellent comprehensive properties, including electrical activity, chemical and weather resistance, as well as biocompatibility, assure their applications for actuators dealing with high power (mechanical arm or artificial muscle) and sensors working under severe circumstances (high pressure or high irradiation) [12,13,14,15]. However, PVDF-based FPs represented by P(VDF-TrFE) (poly(vinylidene fluoride-trifluoroethylene)) and P(VDF-TrFE-CTFE)s (CTFE refers to chlorotrifluoroethylene) usually possess a high Y of 0.3~0.4 GPa for their semi-crystalline structure, thus delivering a relatively low electromechanical efficiency ( ε r /Y ).…”