High-temperature polymer conductors with self-assembled conductive pathways

Abstract Although conducting polymer composites have been active for several decades, the high percolation threshold and low operation temperature greatly limit their applications. We report a general and highly scalable strategy to make low percolation threshold and high-temperature polymer conductors composed of self-assembled carbon black (CB) networks in polyoxymethylene matrix. Our results demonstrated that the self-assembly properties of conductive particles in polymer melts can be tuned via adding a small amount (1 wt%) of polyamide copolymer, which has much stronger interaction with CB and lower viscosity compared with polymer matrix. The bridging polyamide chains which have a much higher melting point linked the CB particles together into conductive pathways, not only dramatically reducing the percolation threshold, but also retaining structural integrity and strong bonding even at elevated temperatures, and thus the composites have stable resistivities across a wide temperature range. Furthermore, due to the existence of polyamide chains in the CB networks, a remarkable enhancement in thermal stability of composites was obtained by the combined effects of physical isolation and chemical adsorption of reactive groups or free radicals. The present method offers an unprecedented opportunity for the development of low percolation threshold and high-temperature polymer conductors.