GRAPHENE OXIDE BASED TRANSPARENT RESINS FOR ACCURATE 3D PRINTING OF CONDUCTIVE MATERIALS

Digital Light Processing (DLP) allows the fast realization of 3D objects with high spatial resolution. However, DLP is limited to highly transparent resins, and therefore not well suited for printing electrically conductive materials. Manufacturing conductive materials would significantly broaden the spectrum of applications of the DLP technology. But conductive metal or carbon based fillers absorb and scatter light; inhibiting thereby photopolymerization, and lowering 3D printing resolution. In this work, UV transparent liquid crystal graphene oxide (GO) is used as precursor for generating in-situ conductive particles. The GO materials are added to a photopolymerizable resin via an original solvent exchange process. By contrast to earlier contributions, the absence of drying during the all process allows the GO material to be transferred as monolayers to limit UV scattering. The absence of UV scattering and absorption allows for fast and high-resolution 3D printing. The chosen resin sustain high temperature to enable an in-situ efficient thermal reduction of GO into reduced graphene oxide rGO which is electrically conductive. The rGO particles form percolated networks with conductivities up to 1.2·10-2 S·m-1. The present method appears therefore as a way to reconcile the DLP technology with the manufacturing of 3D electrically conductive objects.