Dispersion of Multi-walled Carbon Nanotubes in Aqueous Pluronic F127 Solutions for Biological Applications

Because mass-produced carbon nanotubes (CNTs) are strongly aggregated and highly hydrophobic, processes to make them water soluble are required for biological applications. Suspensions in surfactant solutions are often employed. Among these, Pluronic F127 appear to be highly biocompatible if used at low concentrations. Starting from these results, this work involves a systematic study to clarify the dispersion behaviour of CNTs in Pluronic F127. The results suggest a two-step process: first, the bundles disaggregate, kinetically driven by the energy supplied to the system; second, they disperse (surfactant adsorption), thermodynamically driven by the surfactant concentration. The dispersion reaction data are well fitted by a first-order kinetics reaction. By performing a pretreatment step, consisting of stirring at 70C, the achieved concentration of CNTs in solution is twice that of the traditional process. The proposed procedure provides an optimal compromise between a low Pluronic concentration and a high CNT concentration.