Uses of Fullerenes and Carbon Nanotubes

Bonding, structure, and the properties of matter • Structure and bonding of carbon

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Why does functionalisation matter for medical uses?

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Functionalisation increases water solubility, reduces toxicity and enables targeting of specific cells or tissues.

Key concepts

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Definition and structural basis

Fullerenes are spherical or cage-like carbon molecules in which each carbon atom bonds to three others, forming pentagons and hexagons. Carbon nanotubes are cylindrical tubes formed from rolled graphene sheets; single-walled nanotubes (SWNTs) contain one tube, while multi-walled nanotubes (MWNTs) contain several concentric tubes. The curved sp2 bonding in these structures changes electrical and mechanical behaviour compared with flat graphite.

Electrical and thermal properties

Delocalised pi electrons along the curved carbon network enable electrical conductivity in many nanotubes and some fullerene derivatives. Semiconducting or metallic behaviour in nanotubes depends on tube diameter and chirality, causing selective use in nanoelectronics. High phonon transport along the tube axis causes high thermal conductivity, supporting uses as thermal management materials.

Mechanical strength and composites

Strong covalent bonding and tubular geometry give carbon nanotubes exceptionally high tensile strength and stiffness per unit mass. Addition of nanotubes to polymer, ceramic or metal matrices increases composite strength and reduces weight. Effective load transfer results only when nanotubes disperse evenly and align well in the matrix; poor dispersion or weak interfacial bonding limits mechanical improvement.

Uses in medicine and drug delivery

Hollow fullerene cages and functionalised nanotubes provide high surface area for drug loading and controlled release. Chemical functionalisation improves water solubility and targeting, causing potential use as drug carriers and in imaging contrast agents. Safety and biocompatibility concerns limit clinical deployment until toxicity, biodistribution and long-term persistence receive thorough evaluation.

Electronics, sensors and energy storage

Metallic nanotubes serve as nanoscale interconnects and electrodes because of their conductivity and small diameter; semiconducting nanotubes form components in transistors and sensors. High surface area and electrical conductivity cause use of nanotube-based electrodes in supercapacitors and lithium-ion battery electrodes. Scalability, reproducible electronic type control and contact resistance remain limiting factors for widespread commercial adoption.

Catalysis, adsorption and lubrication

Large surface area and electron-accepting behaviour of some fullerenes make them effective in catalytic processes and as adsorbents for gases. Spherical fullerenes and nanotubes reduce friction when used as additives because their shapes allow rolling or layering between sliding surfaces. Chemical stability and potential aggregation affect performance in real systems.

Key notes

Important points to keep in mind

Fullerene cages and nanotube geometry produce unique electrical, thermal and mechanical properties.

Functionalisation improves solubility and biocompatibility but can change intrinsic properties.

Nanotube dispersion, alignment and interfacial bonding control composite performance.

Chirality determines whether a nanotube is metallic or semiconducting for electronic use.

Toxicity, production cost and reproducibility limit many real-world applications.

High surface area makes fullerenes and nanotubes effective for adsorption, catalysis and electrode materials.

Aggregation reduces effective surface area and lowers performance in composites and electrodes.

Thermal conductivity along nanotube axes enables use in heat management when contact resistance is low.

Controlled functional groups enable targeted drug delivery and improved processability.

Manufacturing scalability and quality control remain key barriers to mass-market adoption.