Search

Polyvinylidenefluoride (PVDF) is a semi‐crystalline ferroelectric polymer with a wide range of interesting properties and shows potentiality in a variety of technological applications. Flexible thin films of PVDF nanocomposites (NCs) have attracted many researchers due to their tunable electronic properties. This paper reports the synthesis, characterization, and dielectric studies of PVDF‐TiO2 NC thin films. The synthesized films are self‐supporting thin and the average thickness of the thin films is 60 µm measured using a Digital thickness gauge of resolution 0.01 mm. TiO2 nanoparticles are prepared using the combustion method. Commercially available PVDF granules are used to develop PVDF‐TiO2 NC thin films using the film casting technique. The structural study of the prepared thin films is carried out using XRD that confirms the retention of the β‐phase of PVDF. The functional group and bonding nature have been studied using FTIR Spectroscopy. The thermal stability of the NC thin films is studied using TGA. The variation of dielectric constant (DC), dielectric loss (DL), AC conductivity, and dissipation factor of the medium of pristine PVDF and PVDF‐TiO2 NC thin films are studied in the frequency range of 10 Hz to 8 MHz at ambient temperature. The dielectric constant of PVDF‐TiO2 NC thin films increases up to 8 wt% and anomaly for 10 wt% of TiO2 fillers in the PVDF matrix at a lower frequency and found to decrease with increasing frequency. The dielectric loss of NC thin films is high at a lower frequency and decreases with an increase in the frequency that is in good agreement with the Maxwell–Wagner type of interfacial polarization. At lower frequencies, the dielectric constant of PVDF‐TiO2 NC increases with the increase in filler content. AC conductivity shows a sharp increase at higher frequencies whereas the dissipation factor of the polymer NCs remains unaltered with respect to frequency by maintaining the trend. This suggests that PVDF‐TiO2 NC is potential material for energy storage devices. [ABSTRACT FROM AUTHOR]

ZnO NPs are promising options due to their versatile application range in almost every field of science and technology including biomedical sciences. Obtaining stable and structured ZnO NPs is still challenging. The aim of this research is to produce highly stable and structured ZnO NPs through an economic and nontoxic approach. For this purpose, a green route using aqueous leaf extract of Plumeria obtusa L. as a reducing agent at different reaction temperatures (t) and annealing temperatures (T) is implemented. The structural, optical, and thermal properties of ZnO NPs were investigated using various analytical techniques (XRD, SEM, TEM, UV-vis, FTIR, Raman, zeta potential, photoluminescence, and TGA) and validated for their biological applications. The increase in both the temperatures 't' and 'T' resulted in an increase in crystallite size from 20 to 42 nm with a wurtzite structure and the change was observed from the flower to sphere shape. The zeta-potential values between 35.1 and 47.8 mV suggested higher stability and the excess amount of oxygen over zinc depicted the occurrence of p-type semiconducting behaviour in ZnO NPs. The optical bandgap was found to decrease from 3.48 to 2.96 eV with an increase in 't' and 'T' temperatures. More importantly, the ZnO NPs exhibited promising antimicrobial effects on pathogenic bacteria (Klebsiella pneumoniae) and fungi (Aspergillus niger and Rhizopus stolonifer) with inhibition zones of 19 to 26 mm. This study presents an efficient green synthesis route for ZnO NPs with remarkable physicochemical and antimicrobial properties. [ABSTRACT FROM AUTHOR]