Abstract

Polyvinylidene Fluoride (PVDF) and its co-polymer derivatives have been extensively investigated as a thin film piezoelectric material due to its flexibility, which is desired for flexible sensors, wearable devices, tactile sensors, and low-frequency energy harvesters. Researchers are interested to enhance the piezoelectric response as well as the mechanical properties of PVDF and its co-polymer to enhance device performance. This work primarily investigates the solvents used to synthesize the polymer and their effect on the mechanical properties (hardness and elastic modulus) of thin-film co-polymer polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE). Various solvents with varying physicochemical properties were screened for the dissolution of PVDF-TrFE polymer to investigate the effect of solvents to tailor the key properties of the solvents that influences hardness, Young’s Modulus, flexibility, and the piezoelectric response. The hardness of the thin films was also affected by the addition of various nanocomposites. Hence, the hardness and the Young’s Modulus of the thin films with different solvents and ZnO nanocomposite particles was determined via nanoindentation. The thin films were characterized via X-ray diffraction (XRD), and quasi-static piezometer measurements and the thickness of the thin film was determined by a profilometer. The crystallinity of the thin films was enhanced via annealing at 125°C leading to a higher piezoelectric constant. This paper reports that the hardness and the Young’s Modulus of the thin films are highly dependent on the solvent’s physicochemical properties, dipole moment, and the nanocomposite concentration. Our observation revealed that the solvent with the highest dipole moment (HMPA) inherits the highest piezoelectric coefficient. This study demonstrates how manufacturing methods can affect the film’s mechanical and piezoelectric properties which are useful for researchers using PVDF in MEMS devices in the future.

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