Mechanically robust pyrolyzed carbon produced by two photon polymerization

Abstract

Rapid production of nanoscale carbon-based designs with complex 3D geometry has been recently enabled by nano-3D printing via two-photon polymerization (2PP) combined with post-pyrolysis of the printed polymer. Upon pyrolysis, the design is converted to predominantly carbon, but it remains critical to select the appropriate 2PP printing parameters to produce a high stiffness and strength carbon material. Herein, we evaluate the mechanical performance under both tension and compression of 2PP-derived pyrolyzed carbon designed with modified printing parameters and provide the structural insight toward creating a robust and reliable pyrolyzed carbon material. The 2PP printing parameters are found to influence the Young's modulus of the pyrolyzed carbon by the degree of graphitic sp2 bonding in the carbon while the yield strength is dictated by the degree of porosity which influences crack initiation. These mechanisms are dissimilar to the precursor polymer indicating specific design requirements for the pyrolyzed carbon. Additionally, the surface roughness of the pyrolyzed carbon is uniform and ultra-smooth regardless of the precursor polymer conditions. This article thereby provides a template and structural insight towards the creation of a reliable and robust pyrolyzed carbon material that is suitable for the wide range of nano and microscale designs enabled by this technology.