Growth Mechanism of Synthetic Imogolite Nanotubes

By controlling the surface effects during droplet evaporation of imogolite solutions, imogolite nanotubes were dispersed individually and directly observed by transmission electron microscopy (TEM), and the structure evolution of imogolite nanotubes in the synthetic process was investigated. It was found that the number of imogolite nanotubes continuously increased with time in the whole reaction. The average length grew slowly over time after a remarkable increase in the initial 24 h, and the length distribution experienced a similar variation with the polydispersity index always below 2. No appreciable changes in tube diameters were detected under TEM observation. The nutrient diffusion controlled kinetic formation mechanism is favored by our semiquantitative analysis of the experimental results. Adding nanotube “seeds” to a fresh reaction solution promoted further growth of the nanotubes. This served as a consolidated support to the proposed kinetic controlled mechanism.