Abstract
This study was dedicated to the investigation of poly(vinylidene fluoride) (PVDF) micropillar arrays obtained by soft lithography followed by phase inversion at a low temperature. Reduced graphene oxide (rGO) was incorporated into the PVDF as a nucleating filler. The piezoelectric properties of the PVDF-rGO composite micropillars were explored via piezo-response force microscopy (PFM). Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) showed that α, β, and γ phases co-existed in all studied samples, with a predominance of the γ phase. The piezoresponse force microscopy (PFM) data provided the local piezoelectric response of the PVDF micropillars, which exhibited a temperature-induced downward dipole orientation in the pristine PVDF micropillars. The addition of rGO into the PVDF matrix resulted in a change in the preferred polarization direction, and the piezo-response phase angle changed from −120° to 20°–40°. The pristine PVDF and PVDF loaded with 0.1 wt % of rGO after low-temperature quenching were found to possess a piezoelectric response of 86 and 87 pm/V respectively, which are significantly higher than the |d33eff| in the case of imprinted PVDF 64 pm/V. Thus, the addition of rGO significantly affected the domain orientation (polarization) while quenching increased the piezoelectric response.
Highlights
Poly(vinylidene fluoride) (PVDF) is a well-known ferroelectric polymer with many promising properties and applications in micro electro mechanical systems (MEMS)
The results of this study provided a qualitative indication of the enhancement of the piezoelectric response of poly(vinylidene fluoride) (PVDF) micropillar arrays loaded with Reduced graphene oxide (rGO) and quenched at −20 ◦ C
87 pm/V for the quenched neat PVDF sample and the one loaded with 0.1 wt % of rGO respectively, which is substantially higher than a |d33 eff | of 64 pm/V for the imprinted PVDF
Summary
Poly(vinylidene fluoride) (PVDF) is a well-known ferroelectric polymer with many promising properties and applications in micro electro mechanical systems (MEMS). A great deal of research on the crystallization of the β phase in PVDF has been performed, which has superior piezoelectric properties to the γ phase. The β and/or γ crystals in PVDF could be obtained from the non-polar α modification by various processes, such as stretching [8,9], poling under high electric fields [10,11], melt crystallization under high pressure [12,13], or very high cooling rates [14,15,16]. While PVDF films formed by conventional methods, such as melt casting and spin coating, primarily consist of the α-phase [17], those obtained by phase inversion are dominated by the β-phase [16]
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