Interfacial Engineering of Fluoropolymers Towards Higher Piezoelectric, Ferroelectric, and Dielectric Performance for Sensing and Energy Harvesting Applications

Abstract

The electrical properties of pristine fluoropolymers are inferior due to their low polar crystalline phase content and rigid dipoles that tend to retain their fixed moment and orientation. Several strategies such as electrospinning, electrohydrodynamic pulling, and template-assisted growing have been proven to enhance the electrical properties of fluoropolymers, however, these techniques are mostly very hard to scale-up and expensive. Here, we propose a facile interfacial engineering approach based on amine-functionalized graphene oxide (AGO) to manipulate the intermolecular interactions in poly (vinylidenefluoride-trifluoroethylene) (PVDF-TrFE) to induce β-phase formation, enlarge the lamellae dimensions, and align the micro-dipoles. The coexistence of primary amine and hydroxyl groups on AGO nanosheets offers strong hydrogen bonding with fluorine atoms, which facilitates domain alignment, resulting in an exceptional remnant polarization of 11.3 µC cm-2. PVDF-TrFE films with 0.1 wt% AGO demonstrated voltage coefficient, energy density, and energy-harvesting figure of merit values of 0.30 Vm N-1, 4.75 J cm-3, and 14 pm3 J-1, respectively, making it outstanding compared with state-of-the-art ceramic-free ferroelectric films. We believe this work can open-up new insights towards structural and morphological tailoring of fluoropolymers to enhance their electrical and electromechanical performance and pave the way for their industrial deployment in next-generation wearables and human-machine interfaces.