Adillah Nurashikin Arshad

Effect of Annealing Temperature on the Crystallinity, Morphology and Ferroelectric of Polyvinylidenefluoride- Trifluoroethylene (PVDF-TrFE) Thin Film

The annealing temperature for 250 nm PVDF-TrFE (70:30 mol %) spin coated thin films were varied at solvent evaporation (Ts = 79 °C), Curies transition (Tc= 113 °C), till melting temperature (Tm = 154 °C). XRD measurement showed that, there was an improvement in the crystallinity of the annealed films, consistent with the increased in the annealing temperatures. Morphological studies of the annealed PVDF-TrFE thin films as observed with Field Emission Scanning Electron Microscope (FESEM) (100k magnification), showed enhanced development of elongated crystallite structures known as ferroelectric crystal. However, thin film annealed at 160 °C (AN160) showed fibrous-like structure with appearance of nanoscale separations, which suggested high possibility of defects. Ferroelectric characterization indicated an improvement in the remnant polarization of annealed PVDF-TrFE thin films with the exception to AN160 in which leakage of current was inevitable due to the presence of cracks on the film surface.

Different surface morphology of annealed PVDF-TrFE thin films and the effect on its ferroelectric properties

The different morphology of 250 nm PVDF-TrFE (70:30 mol%) thin films were observed in relation to its ferroelectricity. The annealing temperatures were varied from solvent evaporation (Ts), Curies transition (Tc), up to melting temperature (Tm). It was found that the annealing process promoted the development of elongated crystallite structure also known as ferroelectric crystal, which significantly improved the ferroelectric properties of PVDF-TrFE (70:30 mol%) thin films. However, the presence of nanoscale separations on the thin film annealed over Tm (AN160) suggested high possibility of defects, and hence a reduction in ferroelectric properties of thin films.

Surface Modification of Polyvinylidenefluoride-Trifluoroethylene Film Using Argon Gas Plasma

This study investigates the surface properties of plasma surface modified spin coated PVDF-TrFE (70/30) film using Atomic Force Microscopy (AFM), Water Contact Angle (WCA) and X-ray Photoelectron Spectroscopy (XPS). The surfaces of the spin coated PVDF-TrFE film were modified using 13.56 MHz rf Argon plasma. The exposure time of the charged particle PVDF-TrFE films were varied for 1, 3 and 5mins. Prior to modification, the average surface roughness obtained was 8.615nm, but upon modification, the surface roughness was found to increase to 12.466nm. The value of the contact angle of the modified film was reduced from 90o to 43o and the XPS analysis showed dehydrofluorination of PVDF-TrFE films surfaces. The improved in surface roughness and the increased in wettability of the modified film, resulted in good biocompatibility of the modified PVDF-TrFE thin films. This phenomenon has created interest in researchers for developing functional polymer used for applications in areas such are biomedical, bio-analytical assays, textile and even food industry.

The Study of the Surface Morphology of PVDF/MgO Nanocomposites Thin Films

This study investigates the effect of varying loading percentages of MgO on the topography and morphology of Poly (vinylideneflouride)/Magnesium Oxide (PVDF/MgO) nanocomposites thin films. PVDF/MgO nanocomposites spin coated thin films with thicknesses ranging from 200nm to 456nm were successfully characterized. The nanocomposite solutions were spin coated on Al-glass substrates at 1500rpm. The topography and surface roughness of PVDF/MgO nanocomposites were characterized by using AFM. FE-SEM was used to investigate the surface morphology of the nanocomposites thin films and ATR-FTIR was used to determine the chemical bonding of PVDF/MgO nanocomposites. MgO (7%) was found to be the optimum loading percentage for PVDF/MgO nanocomposite film with favorable distribution of MgO particles, minimum defects and high content of β-phase as evident by FESEM and FTIR.

Effect of various annealing temperature on the morphological and dielectric properties of Polyvinylidenefluoride-Trifluoroethylene thin film

The morphology of PVDF-TrFE (70/30) thin film at various annealing temperature were investigated using non-contact mode Atomic Force Microscopy (AFM). Differential Scanning Calorimetry (DSC) technique was used to obtain T_C, T_m, and T_Crys of PVDF-TrFE. The prepared spin coated PVDF-TrFE (70/30) thin films were annealed at T_C (113°C), T_m (154°C), T_Crys (135°C) and T_c at cooling (55°C) in accordance to the DSC thermogram observed. Impedance Spectroscopy were conducted to study the dielectric characteristic of the thin films in order to substantiate the electrical behavior of the thin films From the results obtained, the thin films exhibited different morphologies depending on the annealing temperatures utilized. Formation of needle-like crsytallite structure was observed film annealed at and over T_m. Thin film re-crystallized at T_C has an optimized dielectric constant of ~7.8 at 10⁴ hz.

Dielectric constant of PVDF/MgO nanocomposites thin films

This study investigates the effect of varying loading percentage of MgO on the dielectric constant of Poly (vinylideneflouride)/Magnesium Oxide (PVDF/MgO) nanocomposite thin films. PVDF/MgO nanocomposite spin coated thin films were successfully fabricated and characterized. PVDF and nanocomposites solutions with loading percentage of MgO at 3, 5, 7, 9, and 11% were spin coated on Al-glass substrates at 1500rpm. The optimum percentage of PVDF/MgO thin film obtained from the dielectric measurement was 7%. The dielectric constant of PVDF/Mg(7%) nanocomposite at frequency 103 Hz was 21, with low dielectric loss and absence of visible film defects, as evident by FE-SEM images. In FTIR, broad bonding peaks at 840 and 880 cm−1 can be observed. Both bonding represented the -CH 2 and -CF 2 groups of PVDF, which indicated high β-phase content that attributed to the increment in the dielectric constant of PVDF/MgO(7%) nanocomposite. The PVDF/MgO(7%) nanocomposite is favorable for low frequency electronic application such as capacitor.

Structural and electrical properties of PVDF-TrFE/ZnO bilayer and filled PVDF-TrFE /ZnO single layer nanocomposite films

Abstract This study investigates the effect of ZnO nanofillers loading ratios on Polyvinylideneflouride-Triflouroethylene/Zinc Oxide (PVDF-TrFE/ZnO) nanocomposites thin films; filled single layer and bilayer film. Both films were produced using a spin coater with ZnO nanofillers of weight percentages 1, 3, 5 and 7%. These films were characterized for their crystal phase change via ATR-FTIR and electrical properties using I-V measurement. The ATR-FTIR for both single layer and bilayer nanocomposites films showed three distinguished peaks at absorption bands of 1400, 1290 and 848 cm−1, evident of the β-phase PVDF-TrFE crystals. The resistivity value recorded for the bilayer PVDF-TrFE/ZnO nanocomposites thin films were significantly higher in comparison to the filled single layer PVDF-TrFE/ZnO nanocomposites film. At 1 wt%, the resistivity value for PVDF-TrFE/ZnO bilayer thin film was 4.34 × 105 Ω cm, relative to 1.50 × 105 Ω cm resistivity value, for the single layer film. Therefore, it is established in this study that PVDF-TrFE/ZnO bilayer film showed enhanced resistivity property at small loading percentage of ZnO nanofillers, suggests that the bilayer film is suitable to be utilized as a dielectric film for storage devices.

Effect of Exposure Time on Plasma Modified Polyvinylidenefluoride-Trifluoroethylene (PVDF-TrFE) Film Surfaces

This study investigates the plasma surface modified spin coated PVDF-TrFE (70/30) film of 200nm thick using Atomic Force Microscopy (AFM), Water Contact Angle (WCA) and Fourier Transform Infrared Spectroscopy (FTIR). The surface of the spin coated PVDF-TrFE film were modified using 13.56 MHz rf Argon plasma. The exposure time of the charged particle on PVDF-TrFE films were varied for 1, 3, 5, 7 and 9mins. Prior to modification, the average surface roughness observed was 3.5nm. However upon modification, the surface roughness was increased to 9.5nm. The contact angle of the surface modified film was reduced from 89° to 58°. The increase in surface roughness and wettability of the modified film provided good biocompatibility. This finding created great interest in developing functional polymer suitable for applications in areas such are biomedical, bio-analytical assays, textile and even food industry.

Ferroelectric Properties of Polyvinylidenefluoride-Trifluoroethylene (PVDF-TrFE) Annealed Thin Film

The annealing temperature for 250nm PVDF-TrFE (70:30 mol %) spin coated thin films were varied at solvent evaporation (Ts = 79°C), Curies transition (Tc= 113°C) till melting temperature (Tm = 154°C). From the XRD measurement, there was an improvement in the crystallinity of the annealed films, consistent with the increased in the annealing temperatures. Morphological studies of the annealed PVDF-TrFE thin films as observed with Field Emission Scanning Electron Microscope (FESEM) (100k magnification), showed enhanced development of elongated crystallite structures better known as ferroelectric crystal. However, the AN160 thin film showed fibrous-like structure with appearance of nanoscale separations, which suggested to posed high possibility of defects. Ferroelectric characterization indicated an improvement in the remnant polarization of annealed PVDF-TrFE thin films with the exception to AN160 in which leakage of current was inevitable due to the presence of cracks on the film surface.

The Effect of Annealing Temperatures on the Dielectric Constant of PVDF/MgO Nanocomposites Thin Films

Poly(vinylidene flouride)/nano-magnesium oxide (PVDF/MgO) nanocomposites with MgO loading percentage of (7% wt. %) were annealed with various annealing temperatures ranging from 70°C to 170°C with rapid removal from the oven. From dielectric constant, the samples annealed at temperature of 70°C showed an improvement in the dielectric constant from 21 to 23 at frequency 103 Hz for UN and AN70 respectively. However, as the temperatures were increased, the dielectric constant of PVDF/MgO (7%) was found to decrease. XRD showed the presence of β-phase for PVDF/MgO(7%) sample annealed at 70°C in comparison to unannealed sample, hence PVDF/MgO(7%) film is suitable to be used for low frequency capacitor application.