Work

Non-destructive characterization of structural hierarchy within aligned carbon nanotube assemblies

Year: 2011

Type: article

Abstract: Understanding and controlling the hierarchical self-assembly of carbon nanotubes (CNTs) is vital for designing materials such as transparent conductors, chemical sensors, high-performance composites, and microelectronic interconnects. In particular, many applications require high-density CNT assemblies that cannot currently be made directly by low-density CNT growth, and therefore require post-processing by methods such as elastocapillary densification. We characterize the hierarchical structure of pristine and densified vertically aligned multi-wall CNT forests, by combining small-angle and ultra-small-angle x-ray scattering (USAXS) techniques. This enables the nondestructive measurement of both the individual CNT diameter and CNT bundle diameter within CNT forests, which are otherwise quantified only by delicate and often destructive microscopy techniques. Our measurements show that multi-wall CNT forests grown by chemical vapor deposition consist of isolated and bundled CNTs, with an average bundle diameter of 16 nm. After capillary densification of the CNT forest, USAXS reveals bundles with a diameter >4 μm, in addition to the small bundles observed in the as-grown forests. Combining these characterization methods with new CNT processing methods could enable the engineering of macro-scale CNT assemblies that exhibit significantly improved bulk properties.

Source: Journal of Applied Physics

DOI: 10.1063/1.3584759

Authors: Eric Verploegen, A. John Hart, Michael De Volder, Sameh Tawfick, Khek-Khiang Chia, Robert E. Cohen

Institutions: Massachusetts Institute of Technology, University of Michigan, IMEC, University of Illinois Urbana-Champaign

Language: English

Topic: Carbon Nanotubes in Composites

Subfield: Materials Chemistry

Field: Materials Science

Domain: Physical Sciences

Open Access status: bronze