Superior Performance of Artificial Nacre Based on Graphene Oxide Nanosheets

Natural nacre is well-known by its unique properties due to the well-recognized "bricks-and-mortar" structure. Inspired by the natural nacre, graphene oxide (GO) was reduced by dopamine with simultaneous coating by polydopamine (PDA) in aqueous solution to yield polydopamine-capped reduce GO (PDG). The artificial nacre nanocomposite materials of poly(vinyl alcohol) (PVA) and PDG presenting layered structure had been successfully constructed via a vacuum-assisted assembly process, in which PDG and PVA served as "bricks" and "mortar", respectively. A combination of hydrogen bonding, strong adhesion and friction between PDG nanosheets and PVA chains resulted in enhancements for mechanical properties. The tensile strength, elongation at break, and toughness of PDG PVA nanocomposite reached to 327 +/- 19.3 MPa, 8 +/- 0.2%, and 13.0 +/- 0.7 MJ m(-3), which is simultaneously 2.4, 8, and 7 times higher than that of nature nacre with 80-135 MPa, similar to 1%, and similar to 1.8 MJ(-3), respectively. More interestingly, the obtained nanocomposites demonstrated a high anisotropy of thermal conductivity (k(parallel to)/k(perpendicular to) approximate to 380). Combined with superior mechanical properties and high anisotropy of thermal conductivity make these biomimetic materials promising candidates in aerospace, tissue engineering, and thermal management applications.