Polymeric Nanofibers with Ultrahigh Piezoelectricity via Self -Orientation of Nanocrystals

Piezoelectricity in macromolecule polymers has been gaining immense attention, particularly for applications in biocompatible, implantable, and flexible electronic devices. This paper introduces core shell-structured piezoelectric polyvinylidene fluoride (PVDF) nanofibers chemically wrapped by graphene oxide (GO) lamellae (PVDF/GO nanofibers), in which the polar ss-phase nanocrystals are formed and uniaxially self -oriented by the synergistic effect of mechanical stretching, high -voltage alignment, and chemical interactions. The ss-phase orientation of the PVDF/GO nanofibers along their axes is observed at atomic scale through high resolution transmission electron microscopy, and the ss-phase content is found to be 88.5%. The piezoelectric properties of the PVDF/GO nanofibers are investigated in terms of piezoresponse mapping, local hysteresis loops, and polarization reversal by advanced piezoresponse force microscopy. The PVDF/GO nanofibers show a desirable out -of-plane piezoelectric constant (d33) of 93.75 pm WI (at 1.0 wt % GO addition), which is 426% higher than that of the conventional pure PVDF nanofibers. The mechanism behind this dramatic enhancement in piezoelectricity is elucidated by three-dimensional molecular modeling.