Bioinspired
Hierarchical Alumina–Graphene Oxide–Poly(vinyl alcohol)
Artificial Nacre with Optimized Strength and Toughness
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Abstract
Due to hierarchical organization
of micro- and nanostructures, natural nacre exhibits extraordinary
strength and toughness, and thus provides a superior model for the
design and fabrication of high-performance artificial composite materials.
Although great progress has been made in constructing layered composites
by alternately stacking hard inorganic platelets and soft polymers,
the real issue is that the excellent strength of these composites
was obtained at the sacrifice of toughness. In this work, inspired
by the layered aragonite microplatelets/chitin nanofibers–protein
structure of natural nacre, alumina microplatelets–graphene
oxide nanosheets–poly(vinyl alcohol) (Al<sub>2</sub>O<sub>3</sub>/GO–PVA) artificial nacre is successfully constructed through
layer-by-layer bottom-up assembly, in which Al<sub>2</sub>O<sub>3</sub> and GO–PVA act as “bricks” and “mortar”,
respectively. The artificial nacre has hierarchical “brick-and-mortar”
structure and exhibits excellent strength (143 ± 13 MPa) and
toughness (9.2 ± 2.7 MJ/m<sup>3</sup>), which are superior to
those of natural nacre (80–135 MPa, 1.8 MJ/m<sup>3</sup>).
It was demonstrated that the multiscale hierarchical structure of
ultrathin GO nanosheets and submicrometer-thick Al<sub>2</sub>O<sub>3</sub> platelets can deal with the conflict between strength and
toughness, thus leading to the excellent mechanical properties that
cannot be obtained using only one size of platelet. We strongly believe
that the work presented here provides a creative strategy for designing
and developing new composites with excellent strength and toughness