Polyaniline grafted pullulan: Optical, thermal, structural, and electrical characterization studies in combination with density functional theory calculations

Polyaniline (PANI), a conducting polymer, has great interest for a large number of applications. However, poor processability and mechanical properties limits its usage and many methods like blending, grafting etc. are used to overcome this disadvantage. We have carried out grafting of PANI onto pullulan (PULL) via chemical oxidative polymerization technique. The percentage of grafting is favored by increasing concentration of aniline monomer. The formation of PANI is confirmed through UV–Vis spectroscopic studies. The possible grafting mechanism is studied using Fourier transform infrared spectroscopy and validated by Hartree-Fock density functional theory (HF-DFT) calculations. Further, thermal properties of grafted polymers are studied using differential scanning calorimetry and thermo gravimetric analysis. Using FESEM and x-ray diffraction, structural properties of graft polymer were studied. DC electrical conductivity of grafted polymer is measured from I-V characteristics, shows a significant conductivity which is the highlight of this work.