| Popis: |
Protein based composites, such as nacre and bone, show astounding evolutionary capabilities, including tunable physical properties. Inspired by natural composites, we studied assembly of atomistically thin inorganic sheets with genetically engineered polymeric proteins to achieve mechanically compliant and ultra-tough materials. Although bare inorganic nanosheets are brittle, we designed flexible composites with proteins, which are insensitive to flaws due to critical structural length scale (∼2 nm). These proteins, inspired by squid ring teeth, adhere to inorganic sheets via secondary structures (i.e., β-sheets and α-helices), which is essential for producing high stretchability (59 ± 1% fracture strain) and toughness (54.8 ± 2 MJ/m3). We find that the mechanical properties can be optimized by adjusting the protein molecular weight and tandem repetition. These exceptional mechanical responses greatly exceed the current state-of-the-art stretchability for layered composites by over a factor of three, demonstrating the promise of engineering materials with reconfigurable physical properties. Agency for Science, Technology and Research (A*STAR) Nanyang Technological University Published version M.V., T.M., O.C., and M.C.D. were partially supported by DARPA (D19AC00016), Airforce Office of Sponsored Research (FA9550-18-1-0235), Army Research Office (W911NF-16-1-0019), and Huck Endowment of Pennsylvania State University. D.L. and H.G. acknowledge a research start-up grant (002479-00001) from Nanyang Technological University and the Agency for Science, Technology and Research (A*STAR) and the use of the A*STAR Computational Resource Centre, Singapore (ACRC) and National Supercomputing Centre, Singapore (NSCC). |
