Highly electro-conductive PEDOT based thermoplastic composites: effect of filler form factor on electrical percolation threshold

Abstract In previous studies, the synthesis of conductive PEDOT particles was carried out to incorporate them into thermoplastic matrices without relying on commercial PEDOT:PSS solutions or carbon- or metal-based additives. While promising conductivities were achieved, a high filler content was required to reach the percolation threshold. To reduce this filler content, the particle form factor appears to play a crucial role. To investigate this effect, rod-like particles were synthesized via supported polymerization of EDOT. Subsequently, thermoplastic composites were produced through melt-extrusion, blending PEO as the thermoplastic matrix with PEDOT-based fillers, resulting in a conductive thermoplastic material strip. The present study focuses on the synthesis of silica nanoparticles using the Stöber method, followed by the supported polymerization of EDOT to obtain electrically conductive silica@PEDOT nanoparticles. A comparison of percolation curves and percolation thresholds for three different fillers, exhibiting low to high form factors, was performed. Additionally, relationships between processing conditions, morphology, and material properties were analysed using SEM, TEM, TGA, and four-probe resistivity measurements.