Influence of core–shell structured conductive fillers on the electromechanical properties of ferroelectric nanocomposites

Although the ultra-large induced strain of ferroelectric polymers has been achieved under an electric field near breakdown strength, the high driving voltage has been a long-standing obstacle for their safety applications in the actuator, transducer, wearable devices. To resolve this issue, novel core–shell structured CNT–Al₂O₃ nanoparticles grown via atomic layer deposition are utilized to improve the electromechanical properties of P(VDF-TrFE)-based nanocomposites under low applied fields. The electric coercive field (E_c) of nanocomposites substantially decreased with increase in fillers, giving rise to the boosted polarization and induced strain at low electric field. Accordingly, the nanocomposite with 1.1 wt% CNT–Al₂O₃ exhibited a 600% increase in transverse induced strain than that of the neat P(VDF-TrFE). For an identical induced strain, the required driving voltage of the nanocomposite could be effectively reduced by up to 200%. By numerically calculating electric field distribution and polarization, it was revealed that the higher ferroelectric property and lower driving voltage resulted from the enhanced interfacial polarization and the reduced field intensity to switch the polarization of the nanocomposites. This study provides a new route to improve the performance of ferroelectric polymers and holds great promise for using ferroelectric nanocomposites with low operating voltage in practical applications, including portable microfluidic and electronic devices. Graphical abstract: To reduce the driving voltage, a novel core–shell structured CNT–Al₂O₃ nanoparticle filler was utilized to improve the electromechanical properties of P(VDF-TrFE)-based nanocomposites under the low applied electric field. The introduction of CNT–Al₂O₃ filler in nanocomposite could significantly reduce the required electric field intensity for switching the polarization. Owning to its lowest E_c and higher polarization, the transverse induced strain of 1.1 wt% nanocomposite increased by 600% than that of the neat P(VDF-TrFE). [Figure not available: see fulltext.]