MOTT’S VARIABLE RANGE HOPPING MODEL FOR POLYPYRROLE-PAPAIN COMPOSITE POLYMER: INFLUENCE OF PAPAIN ENZYME ON COMPOSITE POLYMER

Abstract

Pure polypyrrole (ppy) doped with different weight percent of papain was synthesized by in situ polymerization. These different compositions of pyrrole and papain composite polymers were analyzed for direct current (DC) conductivity. The size of the particle calculated by using the Scherrer equation and Williamson-Hall (W-H) plot was found to be in the range of 15 nm – 20 nm. Activation energies evaluated by using Arrhenius plots show an increase in activation energy from base ppy to papain-ppy composite polymer. The activation energy was found to vary from 22.4 meV to 34.4 meV for papain-ppy composite. The experiment revealed that Mott’s Variable Range Hopping model (VRH) for three dimensions (3D) applies to pure polypyrrole and papain-ppy composite. The density of states at the Fermi level N(EF) were found to be 2.7 × 1021 eV–1cm–1 for pure ppy and ranged from 0.3 ×1019 eV–1cm–1 to 0.8 ×1020 eV–1cm–1 for the composite polymer. The average hopping range and average hopping energy of pure ppy and composite polymers were also calculated.