Poly(m-aminophenol)/functionalized multi-walled carbon nanotube nanocomposite based alcohol sensors

Carboxyl-functionalized multi-walled carbon nanotube (c-MWCNT) reinforced poly(m-aminophenol (PmAP) nanocomposite film was fabricated by in-situ chemical oxidation polymerization of m-aminophenol in presence of c-MWCNTs, and exploited it as an effective sensor material for detection of aliphatic alcohols. The presence site-selective interaction between the conjugated PmAP chain and the π-bonded surface of c-MWCNT was confirmed by Fourier transform infrared (FT-IR) and Raman spectroscopy. The morphological analysis of the nanocomposite showed the formation of PmAP coating (thickness ∼100 nm) on the CNT surfaces. The X-ray and electron diffraction patterns of the nanocomposites indicated the crystalline nature of the PmAP matrix. The nanocomposite with small quantity of c-MWCNT (2 wt%) was found to have sensing response about 114% and 96% higher than that of pure PmAP for methanol and ethanol vapor (90 ppm). This dramatic improvement of sensing performance might be attributed to the favorable interactions of c-MWCNTs with conjugated PmAP chains that subsequently generate a pathway for possible H-bonding/dipole interaction with the alcohol molecules. The nanocomposite sensor also exhibits distinct features of the response curves and responsivity values for different aliphatic alcohols, which could be used as a basis for the selective detection of these pollutant vapors. The UV–vis and FT-IR analyses were used to explain the sensing mechanism.