Poly(o-anisidine)–tin oxide nanocomposite: Synthesis, characterization and application to humidity sensing

Poly(o-anisidine)–tin oxide (POA–SnO2) nanocomposites have been synthesized for the first time through an in situ chemical polymerization of o-anisidine in the presence of SnO2 nanoparticles of 25–40 nm in diameters. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FESEM) were used to characterize the POA–SnO2 nanocomposites. The characterization results confirmed the polymerization of o-anisidine and the strong interaction between POA and SnO2 nanoparticles. Humidity sensing characteristics such as relative humidity (RH)-impedance property, humidity hysteresis, response and recovery times and reproducibility of POA–SnO2 have been investigated. The nanocomposite with 50 wt% SnO2 exhibited better humidity sensing properties than pure POA, such as good sensitivity, fast response (∼87 s), rapid recovery (∼13 s), hysteresis within 4% and excellent repeatability.