Semiconductive poly[N-1,N-4-bis(thiophen-2-ylmethylene)benzene-1,4-diamine]-nickel oxide nanocomposite based ethanol sensor

摘要

This study aims to use the conductivity of a synthetic polymer as the sensing probe for ethanol. In order to enhance the sensitivity of the sensor, a composite of the polymer and nickel oxide (NiO) nanoparticles was formed as it improved the conductivity. This composite exhibited 100 times more conductivity than the neat polymer. The semiconductive nanocomposite of poly [N-1,N-4-bis(thiophen-2-ylmethylene)benzene-1,4-diamine]-nickel oxide (PBTMBDA-NiO) was prepared by in situ chemical oxidative polymerization. The monomer was N-1,N-4-bis(thiophen-2-ylmethylene) benzene-1,4-diamine (BTMBDA). The monomer (BTMBDA), polymer (PBTMBDA), and NiO nanoparticles used in this study were synthesized. The monomer was prepared by refluxing together 2-thiophene carboxaldehyde, benzene-1,4-diamine, and few drops of glacial acetic acid in ethanol medium for 3 h. The polymer, PBTMBDA, was formed by the chemical oxidative polymerization of BTMBDA in chloroform by FeCl3. NiO nanoparticles were prepared by slow addition of aqueous ammonia to anhydrous nickel chloride at room temperature (28 +/- 6 degrees C), and at a pH of 8 under constant stirring condition. The composite was formed by in situ chemical oxidative polymerization of BTMBDA in chloroform by FeCl3 in the presence of the dispersed NiO nanoparticles. The molecular structure of BTMBDA and PBTMBDA were confirmed by nuclear magnetic resonance (NMR) (H-1, C-13, and Dept-90 degrees), Fourier transform infrared spectroscopy, and ultraviolet (UV)-visible spectroscopy. The PBTMBDA and PBTMBDA-NiO nanocomposite were characterized by X-ray diffraction, thermogravimetric analysis, field emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy analysis. The results of characterization studies indicate the strong interaction between PBTMBDA and NiO in the nanocomposite. The broadness of H-1 NMR peaks in PBTMBDA was due to the increased number of monomer units. The disappearance of the peak of alpha-hydrogens on thio