Mechanical agitation induces counterintuitive aggregation of pre-dispersed carbon nanotubes

• Tipo: Artigo em Revista Científica Internacional
• Data: 2017

Autores

Fernandes, RMF (Autor) Outra; Buzaglo, M (Autor) Outra; Regev, O (Autor) Outra; Furo, I (Autor) Outra; Eduardo F Marques (Autor) FCUP

Revista

Título: Journal of Colloid and Interface Science

Vol. 493

Páginas: 398-404

ISSN: 0021-9797

Editora: Elsevier

Indexação

ISI Web of Knowledge - 8 Citações

Scopus - 8 Citações

Outras Informações

ID Authenticus: P-00M-MCP

DOI: 10.1016/j.jcis.2017.01.040

Abstract (EN): Mechanical agitation is commonly used to fragment and disperse insoluble materials in liquids. However, here we show that when pristine single-walled carbon nanotubes pre-dispersed in water are subject to vortex-shaking for very short periods (typically 10-60 s, power density similar to 0.002 W mL(-1)), re-aggregation counterintuitively occurs. The initial dispersions are produced using surfactants as dispersants and powerful tip sonication (similar to 1 W mL(-1)) followed by centrifugation. Detailed imaging by light and electron microscopies shows that the vortex-induced aggregates consist of loose networks (1-10(2) pm in size) of intertwined tubes and thin bundles. The average aggregate size increases with vortexing time in an apparently logarithmic manner and depends on the dispersant used, initial concentration of nanotubes and size distribution of bundles. The aggregation is, nonetheless, reversible: if the vortex-shaken dispersions are mildly bath-sonicated (similar to 0.03 W mL(-1)), the flocs break down and re-dispersal occurs. Molecular insight for the mechanism behind this surprising phenomenon is put forth.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 7