Nanocomposites, multiphase solid materials with at least one nanoscaled component, have been attracting ever‐increasing attention because of their unique properties. Graphene is an ideal filler for high‐performance multifunctional nanocomposites in light of its superior mechanical, electrical, thermal, and optical properties. However, the 2D nature of graphene usually gives rise to highly anisotropic features, which brings new opportunities to tailor nanocomposites by making full use of its excellent in‐plane properties. Here, recent progress on graphene/polymer nanocomposites is summarized with emphasis on strengthening/toughening, electrical conduction, thermal transportation, and photothermal energy conversion. The influence of the graphene configuration, including layer number, defects, and lateral size, on its intrinsic properties and the properties of graphene/polymer nanocomposites is systematically analyzed. Meanwhile, the role of the interfacial interaction between graphene and polymer in affecting the properties of nanocomposites is also explored. The correlation between the graphene distribution in the matrix and the properties of the nanocomposite is discussed in detail. The key challenges and possible solutions are also addressed. This review may provide a constructive guidance for preparing high‐performance graphene/polymer nanocomposite in the future.

Nature is very successful in designing strong and tough, lightweight materials. Examples include seashells, bone, teeth, fish scales, wood, bamboo, silk, and many others. A distinctive feature of all these materials is that their properties are far superior to those of their constituent phases. Many of these natural materials are lamellar or layered in nature. With its “brick and mortar” structure, nacre is an example of a layered material that exhibits extraordinary physical properties. Finding inspiration in living organisms to create bioinspired materials is the subject of intensive research. Several processing techniques have been proposed to design materials mimicking natural materials, such as layer‐by‐layer deposition, self‐assembly, electrophoretic deposition, hydrogel casting, doctor blading, and many others. Freeze casting, also known as ice‐templating, is a technique that has received considerable attention in recent years to produce bioinspired bulk materials. Here, recent advances in the freeze‐casting technique are reviewed for fabricating lamellar scaffolds by assembling different dimensional building blocks, including nanoparticles, polymer chains, nanofibers, and nanosheets. These lamellar scaffolds are often infiltrated by a second phase, typically a soft polymer matrix, a hard ceramic matrix, or a metal matrix. The unique architecture of the resultant bioinspired structural materials displays excellent mechanical properties. The challenges of the current research in using the freeze‐casting technique to create materials large enough to be useful are also discussed, and the technique's promise for fabricating high‐performance nacre‐inspired structural materials in the future is reviewed.

Epoxy nanocomposites combining high toughness with advantageous functional properties are needed in many fields.H owever,f abricating high-performance homogeneous epoxy nanocomposites with traditional methods remains ag reat challenge.N acre with outstanding fracture toughness presents an ideal blueprint for the development of future epoxy nanocomposites.Now,high-performance epoxy-graphene layered nanocomposites were demonstrated with ultrahigh toughness and temperature-sensing properties.T hese nanocomposites are composed of ca. 99 wt %o rganic epoxy,w hich is in contrast to the composition of natural nacre (ca. 96 wt % inorganic aragonite). These nanocomposites are named an inverse artificial nacre.T he fracture toughness reaches about 4.2 times higher than that of pure epoxy.T he electrical resistance is temperature-sensitive and stable under various humidity conditions.T his strategy opens an avenue for fabricating high-performance epoxy nanocomposites with functional properties.Ultra-tough and functional epoxy nanocomposites are urgently needed in many engineering areas,s uch as aerospace,b uilding design, transportation, electronics,a nd many others. [1] Thet raditional methods for toughening epoxy matrix, such as solution mixing,m elt blending,a nd in situ polymerization, usually aim to homogeneously disperse the reinforcements of nanomaterials into an epoxy matrix, which are not very successful in obtaining high-performance epoxy nanocomposites. [2] Thet raditional toughening methods are not amenable to tailoring and optimizing the structure of epoxy nanocomposites.Achallenge then remains to develop an ovel approach for constructing high-performance epoxy nanocomposites.N atural nacre,w ith its brick-and-mortar structure consisting of about 96 wt %inorganic aragonite and about 4wt% biopolymer,e xhibits excellent fracture toughness about three orders of magnitude higher than aragonite, [3] providing ab iomimetic inspiration for constructing highperformance materials. [4] Freeze-casting,a lso known as ice templating, is ap romising technique to fabricate composites with three-dimensional (3D) hierarchical architecture,such as nacre-like ceramics, [5] cellular polymeric composites, [6] honeycomb fibers aerogels, [7] graphene aerogels, [8] and self-healing composites. [9] Inspired by the brick-and-mortar structure of nacre,w e fabricated nacre-like epoxy nanocomposites via freeze-casting. Ther esultant nacre-like epoxy nanocomposites are composed of about 99 wt %o rganic epoxy resin. This is the opposite of natural nacresc omposition of about 96 wt % inorganic aragonite.W ec all this kind of nacre-like epoxygraphene nanocomposite as an inverse artificial nacre.T he fracture toughness reaches up to about 4.2 times higher than that of pure epoxy,which is attributed to the synergistic effect from various toughening mechanisms,s uch as crack deflection, crack branching,i nterfacial fiction, and crack bridging. Furthermore,t his inverse artificial nacre shows anisotropic electrical conductivity owing to the lamell...

Inverse nacre-like epoxy-graphene layered nanocomposites inspired by nacre are fabricated via freeze casting. The epoxy-graphene nanocomposites show a toughening mechanism that incorporates crack deflection, branching, and interfacial friction, exhibiting excellent fracture toughness. Furthermore, due to the conductive properties of the continuous graphene-based scaffold, crack propagation can be monitored by detecting variable electrical resistance. The inverse nacre-like epoxy-graphene nanocomposites expand the application of traditional epoxy-graphene nanocomposites in the engineering design of wind devices and in the automotive industry, aerospace, and many other areas. In addition, the nanocomposite's ability to detect cracks could inspire the design of future nanocomposites with self-monitoring capabilities, thus making them more safe and secure.

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