Plastic Metal-Free Electric Motor by 3D Printing of Graphene-Polyamide Powder

3D printing has revolutionized a number of industries, but complete extension to electronics, robotics, and machines has yet to be realized. Current limitations are due to the absence of reliable and facile methods and materials for accessing conductive 3D printed materials. Traditional approaches to conducting nanocomposites (melt-mixing and solution-mixing) require high energy, are time-consuming, or demand functionalization for compatibilization between filler and matrix. Moreover, these methods usually require a high loading of nanofiller to establish a network of conductive particles (high percolation threshold). As such, access to conductive structures using standard 3D printing techniques and easily accessible starting materials is ideal for realizing next generation conductive polymer composites, with the added benefit of tailorability of size and shape of objects produced. Herein we present a facile method to prepare conductive polymer-based powder by assembling graphene oxide nanosheets on the surface of commercial polymer powder, then reduce the nanosheets to render them electrically conductive, and 3D print by selective laser sintering. Importantly, this simple and scalable method allows for polymer particles covered with carbon nanoparticles to be used to 3D print useful electrically conductive structures without a change to processing parameters compared to the polymer particles themselves. The chemical composition and mechanical and electrical properties of the composite materials were characterized, and we report the first example of a working electrostatic motor composed completely of 3D printed pieces, without any metal parts.