Synthesis and characterization of PVDF/PMMA/ZnO hybrid nanocomposite thin films for humidity sensor application

Abstract

This work aimed PVDF/PMMA thin films in a range of ZnO NPs weight ratios that were successfully manufactured via spin coating as high-performance humidity sensors. The films have been characterized to calculate the structure, functional groups, transmittance and optical energy band gap. X-ray diffraction (XRD) structural studies reveal that the prepared films are polycrystalline with hexagonal crystal structures. It was found that the grain size of these films decreases with the increasing weight ratios of zinc oxide nanoparticles. Field emission scanning electron microscopy reveals the homogeneous distribution of zinc oxide nanoparticles in the PMMA/PVDF matrix. EDX was used to investigate the chemical composition of the PVDF/PMMA/ZnO nanocomposite. FTIR test was performed to identify the functional groups in the prepared samples as well as the detection of doping which is added to the samples. The optical energy band gap values were calculated and types of optical transmission and absorption of the films were determined from the optical transmittance spectra. The optical absorption studies in the wavelength range (200−700) nm show that energy band gap values of the prepared films decrease from (4.98–4.28) eV with increasing the ZnO NPs weight ratio. A sensor for relative humidity within the range (31−100) % RH was manufactured by studying the change of electrical properties (capacitive, resistance) and simulating them theoretically. It was found that the PVDF/PMMA/ZnO NPs nanocomposite is highly sensitive to humidity due to the high porosity of the material. The parameters of the sensors, such as response time and retrieval time, were also studied, and it was found that the manufactured sensors have acceptable values for these parameters.