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As conventional structural materials reach their performance limits, one of the major scientifi c challenges for the 21st century is the development of new high performance, multifunctional materials to support advances in diverse strategic fi elds, ranging from building and transportation to energy and biotechnology. [ 1 ] In the process of evolution, nature has found ingenious ways to produce lightweight, strong, and high-performance materials with exceptional properties and functionalities. [ 2 ] Biological materials, such as tooth, bone, and nacre, are complex, hierarchical, heterogeneous nanocomposites providing superior mechanical properties and biocompatibility. Thus, mimicking the architecture of natural/biological materials and structures is a viable approach for designing new materials.Naturally occurring nacre's remarkably high toughness and resilience, given its composition of brittle, inorganic CaCO 3 and biopolymer proteins, has been widely recognized. Nacre is twice as strong and 1000-fold tougher than its constituents. [3][4][5][6][7] Several mechanisms have been reported that contribute to the strength and toughness of nacre. [4][5][6][7] The layered arrangement of platelet-shaped CaCO 3 crystals and proteins into a "bricks-andmortar" structure is the key to nacre's outstanding mechanical properties. [ 8 ] Platelet-like inorganic building blocks are essential elements in biomimetic artifi cial composites, especially when one aims to create a layered "bricks-and-mortar" micro-and/or nanostructure. In previous studies, however, natural clay minerals, ceramic Al 2 O 3 platelets, and TiO 2 layers were used merely to fabricate biologically inspired composites with high mechanical performance without focusing on other functionalities, such as electrical conductivity and biocompatibility. [ 1-3 , 8-15 ] On the other hand, graphene has attracted considerable interest in recent years owing to its extraordinary material properties. [16][17][18] A two-dimensional lattice of sp 2 -bonded carbon that is only one-atom thick, graphene exhibits remarkably high electrical conductivity, thermal conductivity, and mechanical properties that rival the in-plane values of graphite, making it an excellent candidate as the " bricks" for fabricating nacre-like composites.To date, nanosheets of graphene oxide (GO) or reduced graphene oxide (RGO) have been used as nanofi llers to improve the mechanical and electrical properties of polymers, in which the fi ller content is usually lower than 10 wt%. [19][20][21][22][23][24] For these nanocomposites, full exploitation of the extraordinary properties of graphene is limited by low GO or RGO content. For instance, the highest electrical conductivity of RGO/polymer composites reported is 51.2 S m − 1 , [ 24 ] two orders of magnitudes lower than most pure RGO sheets. On the other hand, for nacre, the platelet-shaped CaCO 3 is the dominant phase with a high content of 95 vol%. [ 3 ] We report the preparation of bio-inspired, nacre-like reduced poly(vinyl alcohol)/graphene oxide (R...

The performance of a composite material system is critically controlled by the interfacial characteristics of the reinforcement and the matrix material. Here we report a study on the interfacial characteristics of a carbon nanotube (CNT)-reinforced polystyrene (PS) composite system through molecular mechanics simulations and elasticity calculations. In the absence of atomic bonding between the reinforcement and the matrix material, it is found that the nonbond interactions consists of electrostatic and van der Waals interaction, deformation induced by these forces, as well as stress/deformation arising from mismatch in the coefficients of thermal expansion. All of these contribute to the interfacial stress transfer ability, the critical parameter controlling material performance. Results of a CNT pullout simulation suggests that the interfacial shear stress of the CNT–PS system is about 160 MPa, significantly higher than most carbon fiber reinforced polymer composite systems.

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