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Assembling nanotubes and nanofibres: Cooperativeness in sepiolite–carbon nanotube materials

Fernandes, Francisco M., Ruiz-Hitzky, Eduardo
Carbon 2014 v.72 pp. 296-303
biosensors, carbon, carbon nanotubes, dispersibility, irradiation, nanocomposites, nanofibers, peroxidase, rheological properties, sepiolite, surfactants, ultrasonics
The dispersibility and stability of carbonaceous materials in water is a long-awaited feature expected to boost the use carbon nanotubes (CNT) and other carbon allotropes to an industrial scale. However, wide use of these materials relies on a deep understanding of the underlying mechanisms that govern its stability in aqueous media. This work focuses on a new approach to effectively disperse multi-walled carbon nanotubes (MWCNT) in water making use of clay mineral sepiolite. Such co-dispersion approach is based on a mechanism similar to steric stabilization. It is conducted under ultrasonic irradiation in the presence of the fibrous clay mineral and MWCNT. This strategy, highly dependent on the rheological properties of the co-dispersant, opens a clear pathway to use CNT in aqueous media without the use of surfactants or oxidative treatments, responsible for extensively damaging the CNT outer walls. To assess the feasibility of the proposed approach, MWCNT were dispersed in water under different conditions and the role of sepiolite fibers discussed. Finally, hybrid buckypapers were prepared from stable sepiolite/MWCNT suspensions and used to prepare a horseradish peroxidase biosensor and a PVA:sepiolite:CNT nanocomposite without compromising the carbon nanotubes integrity and performance.