Superior Performance of Artificial Nacre Based on Graphene Oxide Nanosheets.

Abstract

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, ∼1%, and ∼1.8 MJ m-3, respectively. More interestingly, the obtained nanocomposites demonstrated a high anisotropy of thermal conductivity (k∥/k⊥ ≈ 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.