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Graphene, a material consisting of a single layer of carbon atoms, has been touted as the strongest material known to exist, 200 times stronger than steel, lighter than paper, and with extraordinary mechanical and electrical properties. But can it live up to its promise?--Scientists at the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) have developed the first known statistical theory for the toughness of polycrystalline graphene, which is made with chemical vapor deposition, and found that it is indeed strong (albeit not quite as strong as pristine monocrystalline graphene), but more importantly, its toughness--or resistance to fracture--is quite low. Their study, "Toughness and strength of nanocyrstalline graphene," was published recently in Nature Communications.--"This material certainly has very high strength, but it has particularly low toughness--lower than diamond and a little higher than pure graphite," said Berkeley Lab scientist Robert Ritchie. "Its extremely high strength is very impressive, but we can't necessarily utilize that strength unless it has resistance to fracture."--Ritchie, a senior scientist in the Materials Sciences Division of Berkeley Lab and a leading expert on why materials fail, was co-author of the study along with Ashivni Shekhawat, a Miller Research Fellow in his group. Together they developed a statistical model for the toughness of polycrystalline graphene to better understand and predict failure in the material.-"It's a mathematical model that takes into account the nanostructure of the material," Ritchie said. "We find that the strength varies with the grain size up to a certain extent, but most importantly this is a model that defines graphene's fracture resistance."-[F1] Toughness, a material's resistance to fracture, and strength, a material's resistance to deformation, are often mutually incompatible properties. "A structural material has to have toughness," Ritchie explained. "We simply don't use strong materials in critical structures--we try to use tough materials. When you look at such a structure, like a nuclear reactor pressure vessel, it's made of a relatively low-strength steel, not an ultrahigh-strength steel. The hardest steels are used to make tools like a hammer head, but you'd never use them to manufacture a critical structure because of the fear of catastrophic fracture."--As the authors note in their paper, many of the leading-edge applications for which graphene has been suggested--such as flexible electronic displays, corrosion-resistant coatings, and biological devices--implicitly depend on its mechanical properties for structural reliability.--Although pure monocrystalline graphene may have fewer defects, the authors studied polycrystalline graphene as it is more inexpensively and commonly synthesized with chemical vapor deposition. Ritchie is aware of only one experimental measurement of the material's toughness.--"Our numbers were consistent with that one experimental number," he said. "In practical terms these results mean that a soccer ball can be placed on a single sheet of monocrystalline graphene without breaking it. What object can be supported by a corresponding sheet of polycrystalline graphene? It turns out that a soccer ball is much too heavy, and polycrystalline graphene can support only a ping pong ball. Still remarkable for a one-atom thick material, but not quite as breathtaking anymore." --Next, Shekhawat and Ritchie are studying the effects of adding hydrogen to the material. "We don't know a lot about the fracture of graphene, so we're trying to see if it's sensitive to other atoms," he said. "We're finding the cracks grow more readily in the presence of hydrogen."-The research was funded by the DOE Office of Science. Story Source-The above post is reprinted from materials provided by DOE/Lawrence Berkeley National Laboratory. Journal Reference-Ashivni Shekhawat, Robert O. Ritchie. Toughness and strength of nanocrystalline graphene. Nature Communications, 2016; 7: 10546 DOI: 10.1038/NCOMMS10546 Cite This Page: DOE/Lawrence Berkeley National Laboratory. "Graphene is strong, but is it tough? Scientists find that polycrystalline graphene is not very resistant to fracture." ScienceDaily. ScienceDaily, 4 February 2016. <www.sciencedaily.com/releases/2016/02/160204151138.htm>.

Graphene decharging and molecular shielding

A new study sheds light on unique property of 2-D materials -- ability to shield chemical interactions at the molecular level. Discovery of shielding effect allows scientists to control reactivity of molecules, tune activity of catalysts, and construct new generation of carbon materials.--Joint theoretical and experimental study suggested that graphene sheets efficiently shield chemical interactions. One of the promising applications of this phenomenon is associated with improving quality of 2D materials by "de-charging" of charged defect centers on the surface of carbon materials. Another important feature is the ability to control selectivity and activity of the supported metallic catalysts M/C on the carbon substrate.[F11] Researchers studied carbon materials with defects on the surface (such defects represent an active species, which should be shielded). Indeed, the experiments demonstrated that the defects areas are quite reactive and, as one may expect, defect sites retain high activity towards various molecules.--However, as soon as the defects were covered with few layers of graphene flakes, the distribution of reactive centers became uniform (without localized reactivity centers typical for defect areas). In other words, covering of the surface defects with graphene layers has decreased the influence of charged defects and made them "invisible" in terms of chemical interactions at the molecular level.-Story Source-The above post is reprinted from materials provided by Institute of Organic Chemistry, Russian Academy of Sciences. -Journal Reference-A. E. Sedykh, E. G. Gordeev, E. O. Pentsak, V. P. Ananikov. Shielding the chemical reactivity using graphene layers for controlling the surface properties of carbon materials. Phys. Chem. Chem. Phys., 2016; 18 (6): 4608 DOI: 10.1039/C5CP05586E Institute of Organic Chemistry, Russian Academy of Sciences. "Graphene decharging and molecular shielding." ScienceDaily. ScienceDaily, 8 February 2016. <www.sciencedaily.com/releases/2016/02/160208095908.htm>.

[F1]This is what determines how indestructible this may or may not be so the determination would be the size as one factor and the material itself would be the other and what it aggregates with and the covalent effect as well

[F2]NANOCAGE construct deliverying a Payload into the Cell

[F3]When reading this ---this should make one go Hmmm Artificial life and the implication of what that means in regard to the human genome

[F4]NANO Cages with Metals Integrating or aggregating with DNA in the cage

[F5]NANO CAGE with Polymer Delivery in a cage

[F6]This is also strongly implying that the human body is a cauldron and is being used to “Manufacture” chemistry through the exposure of various chemistry being released into the environment as well as hormones and nano ~ and with this in mind since enzymes stimulate a production of chemicals ~ with the interface of fullerenes the with other nano particles and proteins and carbs and lipids will create things that will not be on the periodic table

[F7]The method of how self assembly and delivery of nano into the cells –DNA –Genetic code ~ and tissues and in this compartmentalization can manufacture what ever cocktail or construct the tech will integrate with and or assimilate through the enzymatic reactions that can now be isolated—anything from an infection to an all out break out and the delivery can be anything from a bug bite to a food or air bourne delivery

[F8]This would also be the same using synthetics or other materials that once programmed can then self assemble once the pieces start there assembling they will go as long or as short or as desired and then attach itself to a bigger conduit or extension

[F9]Carbon or Silica would have to be incorporated and if this is a polymer then the carbon would be the most likely material used and if it part of the enzyme then the external would be there not to involve with direct contact but would be there to trigger the energy required or act as a conduit of the flow of energy

[F10]Pay attention to this~ A reactor reacting and at the same time defending or protecting that reaction thus sustaining the activity ~ meaning that this assembling process can be perpetually active and the chemistry that is coming out of this could be ongoing for asl long as the NANOCAGE is intact

[F11]Sugar - carbon

[F12]This is indicating how the construct is based on a DNA strand(s) and how throw self assembly utilizing the DNA to process the program of assembling using god nanoparticles to be shaped into a complex structure of a diamond indicates a controlled creation integrating the tech with DNA

[F13]DNA strands are again being used to control the sequencing and the follow through in the shaping of the 3d object~ this would be a lot like a capacity to repair or reshape potential mechanisms either robotic or synthetic or even over write human DNA as well

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Graphene is strong, but breaks easy

Scientists find that polycrystalline graphene is not very resistant to fracture

Graphene decharging and molecular shielding