A Facile Synthesis of Poly(aniline-co-3-trifluoromethyl aniline) Doped Silver Nanoparticles in Micellar Solution: Its Humidity Sensor Application

Copolymerization of aniline and 3-trifluoromethyl aniline was carried out by in-situ chemical oxidative technique using slow dispersion of silver nanoparticles. The prepared copolymer was characterized by UV–Vis and FTIR spectroscopy, SEM, XRD, electrical conductivity and humidity sensing techniques. UV–Vis spectrum shows absorption bands around 320 and 620 nm respectively corresponding to π–π* and n–π* transitions. Band gap value of the polymers confirms its semiconducting nature. SEM analysis shows highly agglomerated spherical morphology and the particle size ranges from 100 to 200 nm. The XRD pattern shows amorphous nature of nanocomposite. The electrical conductivity of this nanocomposite changes from 1.86 × 10^–9 to 2.86 × 10^–11 S/cm due to the steric effect of trifluoromethyl group. The relative humidity sensing was studied based on the resistance variations due to the absorption of water molecules in the polymer matrices. It was observed from the fabricated sensors that the resistance decreases from 400 to 230 MΩ when the relative humidity (% RH) changes from 17 to 47%.