A highly selective chemical gas sensor based on functionalization of multi-walled carbon nanotubes with poly(ethylene glycol)

A novel highly selective gas sensor was fabricated by a chemical modification of multi-walled carbon nanotubes containing carboxyl groups (MWNT-COOH) with poly(ethylene glycol) (PEG) in the presence of N,N-dicyclohexylcarbodiimide (DCC). The resistance responsiveness of the film samples against various organic vapors was investigated. The graft percentage and vibration spectra were characterized by a thermo-gravimetric analyzer (TGA), a Fourier transform infrared spectroscope (FTIR) and a Raman spectrometer. The experimental results showed that the sensors obtained displayed high chemical selectivity, fast response and good reproducibility or long stability to chloroform vapor, which are attributed to the properties of MWNTs grafted PEG polymers. In addition, a hydrogen bond interaction and a swelling theory were utilized to illuminate the responsiveness.