Mechanical Properties of Diamond Schwarzites: From Atomistic Models to 3D-Printed Structures

Abstract

Triply Periodic Minimal Surfaces (TPMS) possess locally minimized surface area under the constraint of periodic boundary conditions. Different families of surfaces were obtained with different topologies satisfying such conditions. Examples of such families include Primitive (P), Gyroid (G) and Diamond (D) surfaces. From a purely mathematical subject, TPMS have been recently found in materials science as optimal geometries for structural applications. Proposed by Mackay and Terrones in 1991, schwarzites are 3D crystalline porous carbon nanocrystals exhibiting the shape of TPMS. Although their complex topology poses serious limitations on their synthesis with conventional nanoscale fabrication methods, such as Chemical Vapour Deposition (CVD), TPMS can be fabricated by Additive Manufacturing (AM) techniques, such as 3D Printing. In this work, we used an optimized atomic model of a schwarzite structure from the D family (D8bal) to generate a surface mesh that was subsequently used for . This D schwarzite was 3D-printed with thermoplastic PolyLactic Acid (PLA) polymer filaments. Mechanical properties under uniaxial compression were investigated for both the atomic model and the 3D-printed one. Fully atomistic Molecular Dynamics (MD) simulations were also carried out to investigate the uniaxial compression behavior of the D8bal atomic model. Mechanical testings were performed on the 3D-printed schwarzite where the deformation mechanisms were found to be similar to those observed in MD simulations. These results are suggestive of a scale-independent mechanical behavior that is dominated by structural topology.

Mechanical Properties of 3D-Printed Pentadiamond

“…From approximately 5% strain (the beginning of the plateau region in Figure 3(a) and (b)) we can see that in Figure 5, for all structures, all of the pores start to close in a uniform way for both macroscale and atomic structures. This is different from the layer-by-layer deformation mechanism previously observed in the collapse plateau of other atomic-inspired 3D-printed structures [20,21,24]. The similarity of the compression stages in Figure 5 show an agreement in the deformation mechanisms for pentadiamond and diamond3D between two different length scales and different materials.…”

Schwarz P‐surface via isolated sp2 carbon heptagons: Design and properties

“…Stability of the most strained structure, P130‐C672, was tested by molecular dynamics simulation in a short run, 5 ps, by method 1 starting from the temperature 273 K (Figure S6). A longer run time wasn't computationally affordable, but a high stability of various Schwarzites has been already proven by molecular dynamics: octagon based structures D688 and D8bal, NVT equilibration for 100 ps at 10 K, 32 P688, P8bal, G688, and G8bal, NPT equilibration for 100 ps at 10 K, 33 are stable. The fracture strain is sensitive to the temperature, 34 so a separate study for heptagon based Schwarzites stability depending on temperature would be desired in the future.…”

Mechanical properties of 3D printed macroscopic models of schwarzites

“…We concentrated our study on the FDM printer since this methodology has been previously used in this kind of work. [ 5,6,75 ]…”