Flexible nanocomposite films, with cobalt ferrite nanoparticles (CFN) as the ferromagnetic component and polyvinylidene fluoride–trifluoroethylene (PVDF-TrFE) copolymer as the ferroelectric matrix, were fabricated using a blade coating technique. Nanocomposite films were prepared using a two-step process; the first process involves the synthesis of cobalt ferrite (CoFe2O4) nanoparticles using a sonochemical method, and then incorporation of various weight percentages (0, 2.5, 5, and 10%) of cobalt ferrite nanoparticles into the PVDF-TrFE to form nanocomposites. The ferroelectric polar
The flexible, transparent, and low‐weight nature of ferroelectric polymers makes them promising for wearable electronic and optical applications. To reach the full potential of the polarization‐enabled device functionalities, large‐scale fabrication of polymer thin films with well‐controlled polar directions is called for, which remains a central challenge. The widely exploited Langmuir–Blodgett, spin‐coating, and electrospinning methods only yield polymorphous or polycrystalline films, where the net polarization is compromised. Here, an easily scalable approach is reported to achieve poly(vinylidene fluoride‐trifluoroethylene) P(VDF‐TrFE) thin films composed of close‐packed crystalline nanowires via interface‐epitaxy with 1T′‐ReS2. Upon controlled thermal treatment, uniform P(VDF‐TrFE) films restructure into about 10 and 35 nm‐wide (010)‐oriented nanowires that are crystallographically aligned with the underlying ReS2, as revealed by high‐resolution transmission electron microscopy. Piezoresponse force microscopy studies confirm the out‐of‐plane polar axis of the nanowire films and reveal coercive voltages as low as 0.1 V. Reversing the polarization can induce a conductance switching ratio of >108in bilayer ReS2, over six orders of magnitude higher than that achieved by an untreated polymer gate. This study points to a cost‐effective route to large‐scale processing of high‐performance ferroelectric polymer thin films for flexible energy‐efficient nanoelectronics.
more » « less- NSF-PAR ID:
- 10450948
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials
- Volume:
- 33
- Issue:
- 27
- ISSN:
- 0935-9648
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract β phase of PVDF-TrFE was confirmed by x-ray diffraction (XRD). Thermal studies of films showed notable improvement in the thermal properties of the nanocomposite films with the incorporation of nanoparticles. The ferroelectric properties of the pure polymer/composite films were studied, showing a significant improvement of maximum polarization upon 5wt% CFN loading in PVDF-TrFE composite films compared to the PVDF-TrFE film. The magnetic properties of as-synthesized CFN and the polymer nanocomposites were studied, showing a magnetic saturation of 53.7 emu g−1at room temperature, while 10% cobalt ferrite-(PVDF-TrFE) nanocomposite shows 27.6 emu/g. We also describe a process for fabricating high optical quality pure PVDF-TrFE and pinhole-free nanocomposite films. Finally, the mechanical studies revealed that the mechanical strength of the films increases up to 5 wt% loading of the nanoparticles in the copolymer matrix and then decreases. This signifies that the obtained films could be suited for flexible electronics. -
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