Sidewall Functionalization of Carbon Nanotubes as a Method of Controlling Structural Transformations of the Magnetically Triggered Nanocontainer: A Molecular Dynamics Study
T Panczyk and P Wolski and L Konczak and J Narkiewicz-Michalek, JOURNAL OF PHYSICAL CHEMISTRY C, 119, 8373-8381 (2015).
The magnetically triggered nanocontainer, that is, magnetic nanoparticles covalently linked to carbon nanotube tips, is able to make reversible cycles of capping and uncapping of the nanotube inner cavity. The capped form is when the magnetic nanoparticles adhere to the nanotube tips, whereas the uncapped configuration forms when the magnetic nanoparticle shifts to the nanotube sidewall. The feasibility and likelihood of these two structural forms of the nanocontainer depend on the energetic profile associated with the transitions between them. This paper discusses two approaches for controlling that balance: the covalent functionalization of the nanotube sidewalls by incorporation of polar amide groups and noncovalent functionalization based on adsorption of charged fine colloid nanoparticles. Single- and triple-walled carbon nanotubes were analyzed as was the presence of cisplatin molecules encapsulated in the nanotube inner cavities. Both approaches might result in obtaining the preferred energetic balance, that is, a less stable uncapped state and relatively low activation barrier for spontaneous transition from the uncapped to the capped state. However, adsorption of fine colloids turned out to be too weak to provide long- term stability of the system. Amide functionalization provides the best results in terms of the energetic profile, stability, and other system parameters.
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