A chemical sensor for chloromethanes using a nanocomposite of multiwalled carbon nanotubes with poly(3-methylthiophene)

A vapor phase chemical sensor with a viewing area of 0.78 mm2 (diameter 1 mm) is constructed using a novel nanocomposite material made up of multiwalled carbon nanotubes and poly (3-methylthiophene) that shows a change in electrical resistance upon exposure to different chloromethanes. The resistance change is proportional to the concentration of the analyte. The sensor does not respond to methane, acetone, acetaldehyde, benzaldehyde, tetrahydrofuran, methanol and ethanol. The nanocomposite is characterized by well defined transitions in Fourier transform infrared spectroscopy and thermogravimetric analysis. The response time of the sensor is generally about 60-120 s. The sensor is capable of selectivity to any mixture made up of chloromethane and methane. The mechanism of sensing of chloromethanes is discussed.