Worldwide commercial interest in carbon nanotubes (CNTs) is reflected in a production capacity that presently exceeds several thousand tons per year. Currently, bulk CNT powders are incorporated in diverse commercial products ranging from rechargeable batteries, automotive parts, and sporting goods to boat hulls and water filters. Advances in CNT synthesis, purification, and chemical modification are enabling integration of CNTs in thin-film electronics and large-area coatings. Although not yet providing compelling mechanical strength or electrical or thermal conductivities for many applications, CNT yarns and sheets already have promising performance for applications including supercapacitors, actuators, and lightweight electromagnetic shields.

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Carbon Nanotubes: Present and Future Commercial Applications

Department of Materials Science, University of Patras, 26504 Rio Patras, Greece, Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vass. Constantinou Avenue, 116 35 Athens, Greece, Institut de Biologie Moleculaire et Cellulaire, UPR9021 CNRS, Immunologie et Chimie Therapeutiques, 67084 Strasbourg, France, and Dipartimento di Scienze Farmaceutiche, Universita di Trieste, Piazzale Europa 1, 34127 Trieste, Italy

Chemistry of Carbon Nanotubes

Carbon nanotubes (CNTs) hold the promise of delivering exceptional mechanical properties and multi-functional characteristics. Ever-increasing interest in applying CNTs in many different fields has led to continued efforts to develop dispersion and functionalization techniques. To employ CNTs as effective reinforcement in polymer nanocomposites, proper dispersion and appropriate interfacial adhesion between the CNTs and polymer matrix have to be guaranteed. This paper reviews the current understanding of CNTs and CNT/polymer nanocomposites with two particular topics: (i) the principles and techniques for CNT dispersion and functionalization and (ii) the effects of CNT dispersion and functionalization on the properties of CNT/polymer nanocomposites. The fabrication techniques and potential applications of CNT/polymer nanocomposites are also highlighted.

Dispersion and functionalization of carbon nanotubes for polymer-based nanocomposites: a review

Tissue engineering aims at developing functional substitutes for damaged tissues and organs. Before transplantation, cells are generally seeded on biomaterial scaffolds that recapitulate the extracellular matrix and provide cells with information that is important for tissue development. Here we review the nanocomposite nature of the extracellular matrix, describe the design considerations for different tissues and discuss the impact of nanostructures on the properties of scaffolds and their uses in monitoring the behaviour of engineered tissues. We also examine the different nanodevices used to trigger certain processes for tissue development, and offer our view on the principal challenges and prospects of applying nanotechnology in tissue engineering.

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Nanotechnological strategies for engineering complex tissues.

Chemically converted graphene aerogels with ultralight density and high compressibility are prepared by diamine-mediated functionalization and assembly, followed by microwave irradiation. The resulting graphene aerogels with density as low as 3 mg cm(-3) show excellent resilience and can completely recover after more than 90% compression. The ultralight graphene aerogels possessing high elasticity are promising as compliant and energy-absorbing materials.

Ultralight and Highly Compressible Graphene Aerogels

Cobalt oxide (CoOx) nanowires have been broadly explored as advanced pseudocapacitive materials owing to their impressive theoretical gravimetric capacity. However, the traditional method of compositing with conductive nanoparticles to improve their poor conductivity will unpredictably lead to a decrease in actual capacity. The amelioration of the aspect ratio of the CoOx nanowires may affect the pathway of electron conduction and ion diffusion, thereby improving the electrochemical performances. Here, CoOx nanowires with various aspect ratios were synthesized by controlling hydrothermal temperature, and the CoOx electrodes achieve a high gravimetric specific capacity (1424.8 C g−1) and rate performance (38% retention at 100 A g−1 compared to 1 A g−1). Hybrid supercapacitors (HSCs) based on activated carbon anode reach an exceptional specific energy of 61.8 Wh kg−1 and excellent cyclic performance (92.72% retention, 5000 cycles at 5 A g−1). The CoOx nanowires exhibit great promise as a favorable cathode material in the field of high-performance supercapacitors (SCs).

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Mesoporous Cobalt Oxide (CoOx) Nanowires with Different Aspect Ratios for High Performance Hybrid Supercapacitors

Carbon nanotubes are considered short fibers and the nanotube reinforced composites are always analogues of randomly distributed short fiber composites. In contrast, the real structural fibrous composites often contain fiber reinforcements where fibers run continuously through the matrix material. With the recent advance in nanotube growth, vertical arrays of nanotubes in macroscopic lengths have become available and this allows the fabrication of continuous nano-composites that are similar to the continuous fiber composites utilizing the nanotube arrays as the continuous reinforcement in the composites. This provides a chance to take full advantage of the extreme high modulus and strength for the nanotubes in structural composites. Here, this study fabricates continuous nanotube reinforced polydimethylsiloxane (PDMS) composites and shows that under compressive loadings such continuous nanotube composites can generate dramatic increase in the longitudinal modulus and also significantly enhanced damping capability.Copyright © 2008 by ASME

Continuous Carbon Nanotube-PDMS Composites

Recent advances in the production and availability of nanoscale materials has led to a significant interest in the use of
nanoscale fillers in order to augment and tailor material performance in nanostructured composites. A specific area of
interest is the use of high aspect ratio fillers, such as carbon nanotubes (CNT) and carbon nanofibers (CNF) to augment
the damping capacity of nanostructured composites. Previous work has shown the use of high aspect ratio fillers to
significantly enhance the damping capacity at low frequency by more than 100%; however, the enhancement achieved
has been predicated on strain levels in the composite. Our previous studies have indicated a strong strain dependent
response in the nanostructured composites utilizing CNF to augment damping capacity. This is due, in part, to the
random distribution of fiber orientations seen in the nanostructured composites. The random distribution of filler
orientations is thereby relative to the load applied to the composite that results in a critical shear stress thresholds being
surpassed at the nano scale, allowing the filler to slip relative to the matrix, resulting in frictional energy dissipation as
heat and thereby inducing damping to the high aspect ratio filler nanostructured composite. In light of the promise this
technology holds for use in engineered applications requiring specific damping performance, there remains a
fundamental lack in understanding of the precise mechanisms and thereby a lack of ability to accurately predict material
performance, which is limiting application of the technology. This study looks at the effect of the random filler
orientation of CNF included composites and examines the viscoelastic response of the composite specifically
investigating the effect of filler orientation relative to the loading direction and the effect of filler waviness.
Furthermore, this study looks at the strain dependent nature of the viscoelastic response and develops an analytical
modeling tool to look at the effect of the strain dependent viscoelastic response seen in previous studies with the aim of
achieving a better fundamental understanding of the effect of filler orientation and the associated strain dependent nature
of the viscoelastic response seen in high aspect ratio nano- filled composites.

Strain dependent visco-elastic response of CNFs' reinforced epoxy composites

Parasitic reaction driven facile preparation of segregated-MXene/polycarbonate nanocomposites for efficient electromagnetic interference shielding

An aluminum methylmethoxyphosphonate (AlPo)-based flame retardant (FR) was synthesized. Thermal degradation and flame retardancy of nylon 6 (PA6)/AlPo composites were examined and compared with PA6/commercial aluminum diethylphosphinate (AlPi) composites. The PA6/AlPo composite achieved a V-0 rating at 20 wt% loading during the UL-94 test, and it exhibited the formation of a charred layer that protected the polymer from burning and reduced the release of gases during the combustion of PA6. AlPo demonstrated exceptional performance in gaseous and condensed phases in the PA6 matrix, whereas AlPi only worked in the gaseous phase. The differences between the thermal degradation mechanisms and flame retardancies of AlPi and AlPo were investigated via Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and cone calorimetry. A suitable degradation mechanism was proposed to aid the development of flame retardants in the future.

Jonghwan Suhr

Papers

Mesoporous Cobalt Oxide (CoOx) Nanowires with Different Aspect Ratios for High Performance Hybrid Supercapacitors

Continuous Carbon Nanotube-PDMS Composites

Strain dependent visco-elastic response of CNFs' reinforced epoxy composites

Parasitic reaction driven facile preparation of segregated-MXene/polycarbonate nanocomposites for efficient electromagnetic interference shielding

Thermal degradation and flame retardancy of nylon 6/aluminum methylmethoxy phosphonate composites