Ferroelectric P(VDF-TrFE)/POSS nanocomposite films: compatibility, piezoelectricity, energy harvesting performance, and mechanical and atomic oxygen erosion

Abstract

Poly(vinylidene difluoride) (PVDF) and its copolymers as the polymers with the highest piezoelectric coefficient have been widely used as sensors and generators. However, their relatively low performances limit their applications in some harsh environments. In this work, piezoelectric poly(vinylidene-trifluoroethylene) P(VDF-TrFE) matrices with different amounts of polyhedral oligomeric silsesquioxane (POSS) were prepared by a low temperature solvent evaporation method and thermal poling. The morphology, surface performance, crystalline phase, and piezoelectric and ferroelectric properties of the nanocomposites were investigated and the influence of POSS on these performances was studied. POSS had good compatibility with P(VDF-TrFE) and did not affect the crystalline phase formation of the matrix. The composites presented good piezoelectric properties. Piezo- and triboelectric nanogenerators were designed and fabricated. The voltage and current outputs were analyzed and the polarization effect was evaluated. The average output voltage and the current density of the matrix were 3 V and 0.5 μA cm⁻² when subjected to a force of 38 N on an area of 1 cm². The mechanical properties of P(VDF-TrFE)/POSS nanocomposites were also studied by the nanoindentation test. The hardness and modulus of samples increased 20% and 17% with a low addition of POSS. Atomic oxygen erosion properties of the composites were numerically simulated by the Monte Carlo method. The erosion cavity shape and depth were compared and studied. The influence of POSS addition on the P(VDF-TrFE) matrix and the associated reinforcing mechanism were analyzed.