H3PO4-Doped DL-PLA/PANI Conductive Composite for Methane Gas Sensing: Polymer Composite for Gas Sensing

H₃PO₄ doped DL-PLA/PANI conductive composite was prepared by in situ polymerization technique. Room and low temperature DC conductivity were measured by four probe technique and the morphology was analysed by scanning electron microscopy (SEM). Smooth surface for neat DL-PLA and fiber like morphology for H₃PO₄ doped DL-PLA/PANI conductive composite was observed. The average diameter of the fiber in the as prepared composite was found to be 163 nm. The average room temperature conductivity was found to be 0.774 × 10^-3 S/cm and showed ohmic behaviour. Also, low temperature DC conductivity at 77-300 K of as prepared composite shows a temperature dependency. Different electronic transitions were observed in ultraviolet-visible (UV-Vis) region of UV-Vis spectra and direct band gap was calculated using Tauc relation. Polaron band showed emeraldine salt form of H₃PO₄ doped DL-PLA/PANI conductive composite. ATR-FTIR analysis was done for chemical characterization of the polymer. With the prepared DL-PLA/PANI film methane gas sensing was done by varying the concentration. At 500 ppm the response was found to be 9 % at room temperature.