Biodegradable Conductive PLA /Polypyrrole Composite Films With Tunable Percolation Behavior for Flexible Green Electronics

ABSTRACT

Polylactic acid (PLA) is a biodegradable biopolymer with favorable environmental properties, but its inherent electrical insulation restricts its use in electronics and energy storage applications. To overcome this drawback, polypyrrole (PPy), an intrinsically conductive polymer, has been incorporated into PLA to produce conductive and potentially fully biodegradable composite films via a straightforward solution‐casting process. Structural and morphological analyses by Fourier‐transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) confirmed the successful integration of PPy into the PLA matrix. FTIR revealed interfacial interactions consistent with hydrogen bonding, evidenced by shifts in the PLA carbonyl band and the appearance of characteristic pyrrole vibrations, while SEM showed relatively uniform PPy distribution at low PPy loadings. Thermal characterization, performed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), showed an increase in char residue and modified thermal transitions upon PPy incorporation, indicating enhanced high‐temperature stability and changes in the crystallization behavior of PLA. Electrical measurements demonstrated a percolation‐type increase in surface conductivity from the insulating neat PLA to ~10 ⁻¹  S/m at 20 wt% PPy. Mechanical testing revealed a trade‐off between electrical functionality and structural integrity, with tensile strength decreasing from 2.35 MPa for neat PLA to 0.73 MPa at 15 wt% PPy, attributed to progressive particle aggregation at higher loadings. Electrochemical characterization, using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), identified the 5 wt% PPy composition as optimal, combining markedly enhanced conductivity with low polarization resistance, high capacitance, good rate capability, and moderate mechanical properties. These results demonstrate that PLA/PPy films provide tunable electrical, thermal, and mechanical properties while preserving their biodegradability, making them promising candidates for flexible green supercapacitor electrodes, disposable sensors, and other sustainable electronic devices aligned with circular‐economy principles.