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

Carbon nanotube reinforced polymer composites have been extensively researched [Shadler LS, Giannaris SC, Ajayan PM (1998) Appl Phys Lett 73:3842; Ajayan PM, Shadler LS, Giannaris C, Rubio A (2000) Adv Mater 12:750; Wagner HD, Lourie O, Feldman Y, Tenne R (1998) Appl Phys Lett 72:188; Thostenson ET, Chou T-W (2002) J Phys D: Appl Phys 35:L77] for their strength and stiffness properties. The interfaces between nanotubes and polymer matrix can play a critical role in nanocomposites for their mechanical properties, since the interfacial area is order of magnitude more than traditional composites. Unless the interface is carefully engineered, poor load transfer between individual nanotubes (in bundles) and between nanotubes and surrounding polymer chains may result in interfacial slippage [Shadler et al. (1998); Ajayan et al. (2000)] and consequently disappointing mechanical stiffness and strength. Interfacial slippage, while detrimental to high stiffness and strength, could result in very high mechanical damping, which is a hugely important attribute in many commercial applications. In this paper, we show that the mechanical damping is related to frictional energy dissipation during interfacial sliding at the extremely many nanotube-polymer interfaces, and characterize the impact of activation of the frictional sliding on damping behavior.

Utilizing interfaces in carbon nanotube reinforced polymer composites for structural damping

A macroscopic block (∼9mm3) of aligned carbon nanotubes (CNTs) was grown by chemical vapor deposition and its simultaneous electrical conductivity and compressive strain responses were measured parallel and perpendicular to the CNT alignment. The block exhibits elastic moduli of 0.9 and 1.6MPa for compressive strain of <20% in parallel and perpendicular configurations, respectively. The electrical conductivity increases with increasing compressive strain in both configurations. The reversible electrical conductivity and compressive strain responses of block is attributed to elastic bending of CNTs. These excellent properties of CNT block can be used in compressive strain sensing applications.

https://www.rpi.edu/~galld/publications/PDF-files/Gall-60.pdf

Effects of compressive strains on electrical conductivities of a macroscale carbon nanotube block

Sound and vibration damping characteristics in natural material based sandwich composites

This study involves the investigation of mechanical damping and thermal stability of hybrid epoxy composites with two types of fillers, graphitized carbon nanofiber (CNF) and micron size silicon dioxide (SiO2) particles. While viscoelastic properties of the composites were characterized for the study of mechanical damping, the linear coefficient of thermal expansion (CTE) was evaluated for investigation of thermal stability of the hybrid composites. The effect of filler loading was investigated with respect to both mechanical and thermal stability of the hybrid composite materials. It has been found that the addition of 3% weight fraction of SiO2 particles along with 3% weight fraction of CNF can improve damping loss factors by up to 15.6% at room temperature while at the same time improving thermal stability with up to 15% reductions in CTE. This study also presents semi-empirical models which can account for both the fillers in prediction of viscoelastic properties and CTE of the hybrid composites. It is observed that there is reasonable agreement in both mechanical damping and CTE for the hybrid composites between the experimental data and the predicted data.

Jonghwan Suhr

Papers

Utilizing interfaces in carbon nanotube reinforced polymer composites for structural damping

Effects of compressive strains on electrical conductivities of a macroscale carbon nanotube block

Sound and vibration damping characteristics in natural material based sandwich composites

Experimental and analytical investigation of mechanical damping and CTE of both SiO2 particle and carbon nanofiber reinforced hybrid epoxy composites

Observation of High Buckling Stability in Carbon Nanotube Polymer Composites