Increasing the electrical conductivity of carbon nanotube/polymer composites by using weak nanotube–polymer interactions

A weak interaction between carbon nanotubes (CNTs) and polymers was found to reduce polymer-wrapping on CNT surface, decrease the contact resistance between CNTs, and increase the electrical conductivity of their composites. Thermodynamic properties such as surface energy of components, filler–polymer interactions, and wettability of carbon/polymer systems were analyzed. It was found that the graphitized CNTs filled polyoxymethylene (POM) system exhibits the weakest CNT–polymer interaction among all the investigated systems and a poor wettability. Consequently, the graphitized CNT/POM composites possess a high electrical conductivity and a low percolation threshold of 0.5 wt.% CNT loading, which is associated with the weak CNT–polymer interaction, low contact resistance between CNTs, good connectivity of CNT networks, and high crystallinity of POM in the composites. The results obtained imply that high-performance composites with optimal CNT-network structures can be designed and fabricated by fully considering the surface properties of components and CNT–polymer interactions.