Carbon black instead of multiwall carbon nanotubes for achieving comparable high electrical conductivities in polyurethane-based coatings

In this work, we present a simple, reproducible and efficient method for the preparation of uniform and compact highly conductive coatings obtained from surfactant-free water-based mixtures of micro-beads made of cross-linked polyurethane (PU) with either carbon black (CB) or multiwall carbon nanotubes (MWNTs). Low percolation thresholds, 2.9 wt.% with CB and 0.8 wt.% with MWNTs, and high saturated conductivities, 200 S/cm for PU/CB and 500 S/cm for PU/MWNT, were achieved. This finding shows that, firstly, highly conductive carbon-based nanocomposite coatings can be made in water without surfactants using N-methylpyrrolidinone (NMP) as dispersing aid, and, secondly, carbon black can be used in place of multiwall carbon nanotubes for making cheaper coatings without sacrificing the electrical performance.