2D carbon microlattices: A flexible, self-supporting, full-carbon building block

This work presents a demonstration of fabrication and characterization of 2D carbon microlattices (2D-CMLs) with tailored physical properties. The 2D-CMLs are composed of a thin film of pyrolytic carbon embedded with square and diamond micropatterns and variable thickness to tune its mechanical and functional response. The 2D-CMLs can be handled without substrate, springing elastically, bearing load and yet classifiable as bulk carbon materials rather than assemblies of nanocarbons. Utilizing vat photopolymerization (VPP), a reproducible fabrication process for 2D-CMLs is developed, which ensures the absence of apparent structural distortions such as wrinkles, curling, and other off-plane deformations during and after printing as well as pyrolysis. The resulting 2D-CMLs have relative densities $\overline{\rho }$ ∼0.6 and exhibit remarkable electrical conductivity, with values ranging from σ_e= 10,000–13,000 S･m⁻¹. Mechanical properties are excellent as well, reaching tensile strength σ= 27.35 ± 3.08 MPa and stiffness E = 7.68 ± 2.18 GPa for the thick diamond pattern, and σ= 63.32 ± 5.75 MPa and E = 16.12 ± 2.81 GPa for the thin square pattern. Moreover, the 2D-CMLs endure 1000 cycles of bending larger than 90˚ without mechanically degrading. These properties highlight the suitability of our 2D-CMLs for applications requiring multifunctional properties, such as conductivity, strength and flexibility. The outcomes of this study hold significant implications for research aiming at various applications such as flexible electrodes, mechatronics, and sensing, especially under extreme conditions where non-crystalline carbon can be more stable than metals and other popularly used materials.