Preparation and characterization of electrically conductive multiwalled carbon nanotube/polyoxazoline nanocomposite films using spray coating

Multiwalled carbon nanotube/poly(2-ethyl-2-oxazoline) (MWCNT/PEtOx) nanocomposites with different MWCNT content were successfully prepared by amidation reaction between amine-terminated PEtOx (PEtOx–NH2) and carboxylic acid-functionalized MWCNTs (MWCNT–COOH). First, the living cationic ring-opening polymerization of 2-ethyl-2-oxazoline was initiated by methyl p-toluenesulfonate and terminated with ammonia to obtain PEtOx–NH2. Then, amidation reaction between amino groups of PEtOx–NH2 and carboxylic acid groups of MWCNT–COOH was carried out to obtain MWCNT/PEtOx nanocomposites. Finally, nanocomposite films were deposited by spray coating on glass substrates. The structural, thermal, morphological, and electrical properties of the nanocomposites and their films were investigated in detail by gel permeation chromatography, nuclear magnetic resonance, Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, field emission scanning electron microscopy, and two-point probe digital multimeter. All nanocomposites showed higher thermal stability than neat polymer, whereas the spray-coated nanocomposite films exhibited well-dispersed morphology and enhanced electrical conductivity with increase in MWCNT content.