Balancing Conductivity and Morphology in Aniline-Tuned Biopolymer-Starch Composites

This work investigates the optimization of aniline content in polyaniline (PANI)/sago starch blends prepared via in situ oxidative polymerization under ultrasonic irradiation. Building upon our previous optimizations of pH and sonication time, this study focuses on the effect of aniline concentration (5-65 wt%) on electrical conductivity, morphological dispersion, and thermal stability. Various characterization techniques, including field emission scanning electron microscopy (FE-SEM), ultraviolet-visible (UV-Vis) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and thermogravimetric analysis (TGA), confirm that a well-connected, conductive network forms at about 35 wt% aniline. Electrical conductivity measurements reveal a pronounced rise from ~1.6 × 10^-8 to ~2.2 × 10^-3 S/cm between 5 wt% and 35 wt% aniline. Conductivity stabilizes above this threshold due to PANI agglomeration. Morphological assessments confirm a shift from smooth, uniform blends at low aniline to rougher, void-filled surfaces when aniline exceeds 50 wt%. TGA shows improved thermal stability with increasing aniline content. These findings highlight an optimum aniline loading of ~35 wt% to achieve synergy between conductivity and structural integrity in biopolymer-based PANI/sago starch composites, offering a pathway to sustainable, high-performance biopolymer-based conductors for applications in sensors, flexible electronics, and electromagnetic shielding.