Reactive Jetting of High Viscosity Nanocomposites for Dielectric Elastomer Actuation

Abstract The layer‐by‐layer nature of additive manufacturing is well matched to the layer construction of stacked dielectric actuators, with inkjet printing offering a unique opportunity due to its droplet‐on‐demand capability, suitable for multi‐material processing at high resolution. This paper demonstrates the use of high viscosity, multi‐material jetting to deposit two‐part reactive inks with functionalized nanofillers to digitally manufacture dielectric elastomers for soft robots with high precision, and shape manipulation. Graphene‐based fillers, including graphene oxide (GO) and thermally reduced graphene oxides (TRGOs), have been incorporated into a polydimethylsiloxane (PDMS) matrix at low loading (below the percolation threshold). Consequently, the dielectric constant of the elastomer dramatically increases (by 97%) compared to neat PDMS, yielding a more than 20‐fold increase in the electric‐field induced electromechanical contraction (from 0.3 to 6.7%). This study shows that the oxygen‐functionalities present in GO and TRGOs, which possess a moderate conductivity, improve the dispersion of those fillers in polymer matrices, thus significantly improving the dielectric constant of the polymer composites. Inkjet printing of high‐performance, soft electroactive composites enables high‐speed, reliable fabrication of monolithic artificial muscles (leading to stronger, cheaper, and more capable soft robotic devices) and provides a vital stepping stone towards fully additively manufactured soft robots.