title: Polymeric Nanofibers with Ultrahigh Piezoelectricity via Self-Orientation of Nanocrystals.
abstract: 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 β-phase nanocrystals are formed and uniaxially self-oriented by the synergistic effect of mechanical stretching, high-voltage alignment, and chemical interactions. The β-phase orientation of the PVDF/GO nanofibers along their axes is observed at atomic scale through high resolution transmission electron microscopy, and the β-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 V-1(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.
authors.affiliation: Institute of Microelectronics, Tsinghua University , Beijing 100084, PR China.|Tsinghua National Laboratory for Information Science and Technology, Tsinghua University , Beijing 100084, PR China.
authors.forename: Xia
authors.initials: X
authors.lastname: Liu
authors.affiliation: School of Materials Science and Engineering, Tsinghua University , Beijing 100084, PR China.
authors.forename: Jing
authors.identifier: 0000-0003-0103-9858
authors.initials: J
authors.lastname: Ma
authors.affiliation: Institute of Microelectronics, Tsinghua University , Beijing 100084, PR China.|Tsinghua National Laboratory for Information Science and Technology, Tsinghua University , Beijing 100084, PR China.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Wu
authors.affiliation: Department of Mechanical Engineering, University of California , Berkeley, California 94720, United States.
authors.forename: Liwei
authors.initials: L
authors.lastname: Lin
authors.affiliation: Institute of Microelectronics, Tsinghua University , Beijing 100084, PR China.|Tsinghua National Laboratory for Information Science and Technology, Tsinghua University , Beijing 100084, PR China.
authors.forename: Xiaohong
authors.identifier: 0000-0003-4569-7537
authors.initials: X
authors.lastname: Wang
keywords: PVDF/GO nanofiber; core−shell; piezoelectricity; piezoresponse force microscopy; self-orientation; β-phase