Since the discovery of carbon nanotubes in 1991 by Iijima, there has been great interest in creating long, continuous nanotubes for applications where their properties coupled with extended lengths will enable new technology developments. For example, ultralong nanotubes can be spun into fibres that are more than an order of magnitude stronger than any current structural material, allowing revolutionary advances in lightweight, high-strength applications. Long metallic nanotubes will enable new types of micro-electromechanical systems such as micro-electric motors, and can also act as a nanoconducting cable for wiring micro-electronic devices. Here we report the synthesis of 4-cm-long individual single-wall carbon nanotubes (SWNTs) at a high growth rate of 11 microm s(-1) by catalytic chemical vapour deposition. Our results suggest the possibility of growing SWNTs continuously without any apparent length limitation.

Improved electron transport along a carbon nanotube (CNT) fiber when it is spun from an array of longer nanotubes is reported. The effect of chemical post‐treatments is also demonstrated. For example, the covalent bonding of gold nanoparticles to the CNT fibers remarkably improves conductivity (see figure), whereas annealing CNT fibers in a hydrogen‐containing atmosphere leads to a dramatic decrease in conductivity.

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...

From the stone ages to modern history, new materials have often been the enablers of revolutionary technologies.[1] For a wide variety of envisioned applications in space exploration, energy-efficient aircraft, and armor, materials must be significantly stronger, stiffer, and lighter than what is currently available. Carbon nanotubes (CNTs) have extremely high strength, [2][3][4][5] very high stiffness, [6,7] low density, good chemical stability, and high thermal and electrical conductivities.[8]These superior properties make CNTs very attractive for many structural applications and technologies. Here we report CNT fibers that are many times stronger and stiffer per weight than the best existing engineering fibers and over twenty times better than other reported CNT fibers. Additionally, our CNT fibers are nonbrittle and tough, making them far superior to existing materials for preventing catastrophic failure. These new CNT fibers will not only make tens of thousands of products stronger, lighter, safer, and more energy efficient, but they will also bring to fruition many envisioned technologies that have been to date unavailable because of material restrictions. Strong, stiff, and lightweight are critical property requirements for materials that are used in the construction of space shuttles, airplanes, and space structures. These properties are assessed by a material's specific strength and specific stiffness, which are defined as the strength or stiffness (Young's modulus) of a material divided by its density.[9] The combination of high strength, high stiffness, and low density affords CNTs with extremely high values for specific strength and specific stiffness. The most effective way to utilize these properties is to assemble CNTs into fibers. However, despite extensive worldwide efforts to date, the specific strength and specific stiffness of CNT fibers that have been reported by various research groups are much lower than currently available commercial fibers. [10][11][12][13][14][15][16][17][18][19][20][21][22] In early studies, researchers attempted to reinforce polymer fibers with short CNTs, but the reinforcement was limited by several issues, including poor dispersion, poor alignment, poor load transfer, and a low CNT volume fraction. [10][11][12][13][14][15] Recently, pure CNT fibers (also called yarns)were reported with and without twisting. [16][17][18][19][20][21][22] For example, Zhang et al. [20] demonstrated that spinning from aligned CNT arrays could significantly improve the strength of CNT fibers by twisting them. However, to date no breakthrough has been reported in the specific strength and specific stiffness of CNT fibers.Here we report CNT fibers with values for specific strength and specific stiffness that are much higher than values reported for any current engineering fibers as well as previously reported CNT fibers. As shown in Figure 1, the specific strength COMMUNICATION 4198

Arrays of well‐aligned, ca. 4.7 mm long carbon nanotubes (CNTs) are grown in a simple, safe, and cost‐effective manner using an efficient Al2O3/Fe catalyst prepared by an ion‐beam assisted deposition technique (see figure). Importantly, the as‐synthesized CNT arrays with lengths ranging from 500 μm to 1.5 mm are conducive to spinning, and CNT fibers spun from such long CNT arrays show remarkably improved tensile strength.