Ultrastrong Double Walled Carbon Nanotubes Have Been Made and the work was published in Science Advances.

Ultrahigh strength, modulus, and conductivity of graphitic fibers by macromolecular coalescence

Theoretical considerations suggest that the strength of carbon nanotube (CNT) fibers be exceptional; however, their mechanical performance values are much lower than the theoretical values. To achieve macroscopic fibers with ultrahigh performance, researchers developed a method to form multidimensional nanostructures by coalescence of individual nanotubes. The highly aligned wet-spun fibers of single- or double-walled nanotube bundles were graphitized to induce nanotube collapse and multi-inner-walled structures. These advanced nanostructures formed a network of interconnected, close-packed graphitic domains. Their near-perfect alignment and high longitudinal crystallinity that increased the shear strength between CNTs while retaining notable flexibility. The resulting fibers have an exceptional combination of high tensile strength (6.57 GPa), modulus (629 GPa), thermal conductivity (482 W/m·K), and electrical conductivity (2.2 MS/m), thereby overcoming the limits associated with conventional synthetic fibers.

The work was done by researchers in South Korea and Rice University of Texas. There was consultation with Neil Farbstein of the Clean Energy Research Foundation. Neil patented the coalescence process in a 2018 patent.

This was scientific proof of principle of world record-breaking tensile strength fibers in scientific tests published in the April 22, 2022 issue of SCIENCE ADVANCES.

The experiments were based on a method first published in US patent 10,059,595 Ultra High Strength Nanomaterials And Methods Of Manufacture. The theory of macromolecular coalescence of double walled carbon nanotubes (DWNT) was proved to be correct in its predictions. The theory leads to production of carbon fibers with twice the strength of existing graphite fibers. They have very high electrical and thermal conductivity also. “This makes it possible to manufacture much lighter satellites, wind turbine blades, armor, and fuel efficient vehicles. Everything made with carbon fiber
reinforced composites can be made stronger, tougher and lighter using the breakthrough fibers.”

Clean Energy Research Foundation had patent US 10,059,595 issued by the US patent office on August 28, 2018.
They successful tested coalescence processes in the patent.

The patent details
* methods of manufacturing ultra high strength solid objects by macromolecular coalescence of double walled carbon nanotubes
* Methods of manufacturing nanophase ceramics with record breaking strength.
* Methods for ultra tough DWNT membranes, nanopaper, and laminated materials.

Mr. Neil Farbstein said “While the information in the patent was successfully used to make terapascal double strength carbon fibers, we are still looking for investors and R&D partners to help us achieve proof of principle of other embodiments in the patent, including ultra high strength molded solid objects. The patent is available for licensing”

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