Boron Nitride Nanotubes Induced Piezoelectric Coefficient for Polyvinylidene Fluoride-Trifluoroethylene Films by Electrically Assisted Printing

Flexible piezoelectric copolymer films with high piezoelectric coefficient and sensitivity have been developed by electrically assisted printing techniques. Boron nitride nanotubes (BNNTs) serve as nanoscale nucleating agents, significantly promoting β-phase formation and crystallinity in the poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) matrix. The synergistic effects of high-voltage polarization and mechanical stretching during printing align dipoles and optimize microstructure, resulting in a remarkable piezoelectric strain coefficient (d₃₃) of −29.3 pC/N and an exceptional piezoelectric voltage coefficient (g₃₃) of −379.93 mmV/N,which are 2.2 times and 3.7 times higher than those of conventional P(VDF-TrFE) films, respectively. The films exhibit outstanding electromechanical sensing capabilities, generating peak voltages of 600 mV under impact and 2.75 V under bending deformation, alongside improved mechanical strength (12.5 MPa) and thermal stability. These advancements position the films as ideal candidates for next-generation applications in wearable electronics, biomedical diagnostics, and smart infrastructure monitoring, marking a significant leap in the flexible sensing technology.