Design of Light-Weight Three-Dimensional Graphene Assembly

Technology #19224

Questions about this technology? Ask a Technology Manager

Download Printable PDF

Image Gallery
(A) Initial model composed of 500 randomly distributed rectangular graphene flakes and spherical inclusions. (B) Schematics of the graphene with L dimensions that follows a lognormal distribution as given below and spherical inclusion with uniform d in diameter. (C) The targeting temperature T as a function of simulation time in the alternative NPT-NVT ensemble during each equilibration cycle. (D) The targeting pressure p as a function of simulation time in the alternative NPT-NVT ensemble during each equilibration cycle, which is only applicable to the first stage from 0 to 25 ps. (E) The closely packed graphene-inclusion structure obtained after cyclic equilibrations. (F) The equilibrated structure of the 3D graphene assembly after removing the spherical inclusions with dimensions of 11 nm × 11 nm × 11 nm, and the SEM image of a graphene assembly [reproduced from Wu et al. (8)]. Scale bar, 20 μm (inset). (G) The total number of covalent bonds counted at the end of each anneal cycle, averaged by the total number of carbon atoms in the system.(A) Simulation snapshots of the full atomic graphene structure in tension and compressive tests that are taken at εx = −0.5, 0.0, 0.6, and 1.0 for (i) to (iv), respectively. The atomic stress and its distribution at different strain states are computed and included in fig. S3. The symmetric distribution of positive and negative stress suggests that the graphene is largely bent under deformation. Insets show schematics for the different mechanisms of the material behavior under compression and tension. (B) Full stress-strain curve of the material under compression and tension force. (C) The average strains in the two directions other than the loading direction as a function of εx; for |εx| < 0.02, the slope of the curve is measured to be −0.3. For larger deformations, the three linear fits on the plot have slopes of 0.03, −0.6, and 0.04 from left to right of the curve.The normalized Young’s modulus (A), tensile strength (B), and compressive strength (C) of the 3D graphene assembly as a function of its mass density.The data points include mechanical test results of the full atomic 3D graphene assembly (PG), the full atomic gyroid graphene (GG), and the 3D-printed polymer samples (3D-printed). The solid curves are plotted according to scaling laws obtained in the study with slopes of 2.73, 2.01, and 3.01 for (A), (B), and (C), respectively. ρs = 2300 mg/cm3, ES = 1.02 TPa, and σTs = 130 GPa correspond to the density, Young’s modulus, and tensile strength of graphene for its in-plane mechanics, which are used to normalize the properties of graphene materials (PG, GG, and references mentioned). ρs = 1175 mg/cm3, ES = 2.45 GPa, and σTs = 50 MPa correspond to the density, Young’s modulus, and tensile strength of the bulk material properties of polymer material for 3D printing, which are used to normalize the results of 3D-printed samples.(A) Simulation snapshots taken during the modeling of the atomic 3D graphene structure with gyroid geometry, representing key procedures including (i) generating the coordinate of uniformly distributed carbon atoms based on the fcc structure, (ii) generating a gyroid structure with a triangular lattice feature, and (iii) refinement of the modified geometry from a gyroid with a triangular lattice to one with a hexagonal lattice. (B) Five models of gyroid graphene with different length constants of L = 3, 5, 10, 15, and 20 nm from left to right. Scale bar, 2.5 nm. (C) 3D-printed samples of the gyroid structure of various L values and wall thicknesses. Scale bar, 2.5 cm. The tensile and compressive tests on the 3D-printed sample are shown in (D) and (E), respectively.Young’s modulus (A) and tensile strength (B) of the 3D graphene assembly compared to those of porous polystyrene with a woven and foam structure with ρs = 1065 mg/cm3, ES = 3.67 GPa, and σTs = 100 MPa; its scaling laws, Embedded Image and Embedded Image , were obtained from previous studies (20, 21).
Categories
Inventors
Zhao Qin
Department of Civil Engineering, MIT
Professor Markus Buehler
Department of Civil Engineering, MIT
External Link (web.mit.edu)
Min Jeong Kang
Department of Civil Engineering, MIT
Gang Seob Jung
Department of Civil Engineering, MIT
Managed By
Jon Gilbert
MIT Technology Licensing Officer
Patent Protection

Design of Lightweight Three-Dimensional Graphene Assembly

Provisional Patent Application Filed
Publications
The Mechanics and Design of a Lightweight Three-Dimensional Graphene Assembly
Science Advances, January 6, 2017

Applications

Light-weight 3D graphene assembly models can be used in a variety of engineering applications where porous, high strength, low density materials are of use. Furthermore, the combination of computational modeling and 3D printing technology used in this invention can be applied to other areas of engineering research, such as bridge construction or filtration systems.

Problem

The strength of 3D graphene assemblies has been measured in many different experiments by many different labs. The results all indicate that these assemblies have several magnitudes lower tensile strength than what would be predicted by conventional scaling laws. Experimental and computational models that can more accurately predict the strength of these assemblies would not only be able to identify the optimal types of material architecture in graphene, but could also be used to model 3D assemblies comprised of other materials.  

Technology

Graphene is one of the stiffest and strongest materials. By fine tuning the chemical synthesis process, especially the reacting pressure and temperature, many 3D porous graphene structures with different material architectures and densities can be created. These structures’ material properties were characterized by physical experiments to derive new scaling laws that can be used to identify material properties that would lead to the strongest and lightest graphene structures. Variables such as atom connectivity and annealing conditions were identified as crucial factors in creating stronger graphene. Adjusting these values, as well as tuning the surface chemistry of graphene and combining graphene with polymers, can lead to the creation of stronger and lighter materials. In addition, the combination of a theoretical model and computational simulations provides a powerful tool to explore such opportunities for carbon material designs. Finally, the porous atomic geometries that yield the highest strengths from these tests and simulations can be adapted to other areas of engineering, such as large-scale structural materials like concrete, or materials used in filtration system. 

Advantages

  • Ability to create and test a variety of 3D models of graphene
  • Theoretical models to simulate the mechanical response of different materials under loading
  • Accurate predictions of strength based on material architecture
  • Adaptability of modeling paradigm to large-scale applications such as construction and filtration