Facile preparation of highly oriented poly(vinylidene fluoride) uniform films and their ferro- and piezoelectric properties

Abstract

Uniform active films are highly desirable for electronic applications, but still challenging. This work proposed a convenient and effective approach for the production of uniform oriented PVDF thin films with high content of polar b-phase by blade shear. The obtained films not only had a smooth surface, but also achieved uniform component distribution. The results revealed that PVDF crystals preferentially oriented perpendicular to the shear direction and the largest relatively b-phase content was up to 93% calculated from FTIR. It was also found that an appropriate elevated temperature is helpful to the formation of alltrans b-phase with the aid of shear. The oriented uniform PVDF films showed outstanding switching and piezoelectric properties with a polarization switching voltage as low as 3 V and a relatively small coercive field of $6 MV m À1. The observed properties may result from the enhancement of crystallinity of the bphase and the orientation of crystals. The results suggest that oriented PVDF films can be suitably implemented in the fabrication of electronic devices.

Ultrasound-Responsive Nutlin-Loaded Nanoparticles for Combined Chemotherapy and Piezoelectric Treatment of Glioblastoma Cells

“…In fact, the α-phase has characteristic peaks at around 803 cm -1 , whereas the β-phase gives a peak at 848 cm -1 . Also in this case, from the intensities of these two contributions, it is possible to estimate the ratio between the βand α-phase in the sample [38]. In agreement with FTIR, Raman spectroscopy highlights a significant increase of the β-phase in PNPs (β/α = 3), as compared to P(VDF-TrFE) powder (β/α = 2).…”

“…Both bulk P(VDF-TrFE) and PNPs FTIR spectra present the peculiar peaks at 842 and 1279 cm -1 , corresponding to the β-phase of the polymer. The typical peaks of the α-phase arrangement (610, 765, 965 cm -1 ) are very weak and extremely difficult to identify, especially for PNPs (Figure 2c) [38]. This suggests that the polymer preferentially crystallizes in the β-phase.…”

“…where A α and A β represents the absorbance at 765 and 840 cm -1 , respectively, while K α and K β are the corresponding absorption coefficients (K α = 6.1•10 4 cm 2 /mol and K β = 7.7•10 4 cm 2 /mol) [38].…”

Surface Analyses of PVDF/NMP/[EMIM][TFSI] Solid Polymer Electrolyte

“…Unfortunately, the characteristic bands of the α-phase [ 51 ] (854, 975, 1149, 1209, 1383 and 1423 cm −1 ) are weak or located below (410, 489, 532, 614, 763, 795 cm −1 ) the lower limit of our apparatus, which is given by the Ge crystal used. Thus, the fractions of a particular PVDF phase cannot be estimated by the generally accepted approach [ 51 , 53 , 54 , 55 ] based on the α-phase peak at 763 cm −1 . In order to calculate the relative percentage of γ- and β-phases we consider the number of electroactive phases consist only of γ- and β-phases (100%) and use the peak to valley method [ 51 ]: valley of ~1276 cm −1 and peak of 1260 cm −1 for β-phase and valley of ~1232 cm −1 and peak of 1225 cm −1 for γ-phase.…”

Printed recyclable and self-poled polymer piezoelectric generators through single-walled carbon nanotube templating

“…Commonly, phase analysis in literature consists of the intensity ratio of the α and β phase peaks, resulting in a value of zero for pure β phase or infinity for pure α phase. 53,60 To quantify the relative phase content of the β and ɣ phases in the SWCNT/PVDF-TrFE (0.000 wt% to 0.500 wt%) films, a series of equations were used in this study and are shown in eqn (3) and (4), respectively.…”