title: Imaging carbon nanotube interactions, diffusion, and stability in nanopores.
abstract: We report optical microscopy measurements of three-dimensional trajectories of individual multiwalled carbon nanotubes (MWCNTs) in nanoscale silica slit pores. Trajectories are analyzed to nonintrusively measure MWCNT interactions, diffusion, and stability as a function of pH and ionic strength. Evanescent wave scattering is used to track MWCNT positions normal to pore walls with nanometer-scale resolution, and video microscopy is used to track lateral positions with spatial resolution comparable to the diffraction limit. Analysis of MWCNT excursions normal to pore walls yields particle-wall potentials that agree with theoretical electrostatic and van der Waals potentials assuming a rotationally averaged potential of mean force. MWCNT lateral mean square displacements are used to quantify translational diffusivities, which are comparable to predictions based on the best available theories. Finally, measured MWCNT pH and ionic strength dependent stabilities are in excellent agreement with predictions. Our findings demonstrate novel measurement and modeling tools to understand the behavior of confined MWCNTs relevant to a broad range of applications.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: Shannon L
authors.initials: SL
authors.lastname: Eichmann
authors.forename: Billy
authors.initials: B
authors.lastname: Smith
authors.forename: Gulsum
authors.initials: G
authors.lastname: Meric
authors.forename: D Howard
authors.initials: DH
authors.lastname: Fairbrother
authors.forename: Michael A
authors.initials: MA
authors.lastname: Bevan
mesh_terms: D004058:Diffusion; D005898:Glass / Q000737:chemistry; D006046:Gold / Q000737:chemistry; D021621:Imaging, Three-Dimensional / Q000379:methods*; D053768:Metal Nanoparticles / Q000737:chemistry; D008853:Microscopy; D058608:Nanopores; D037742:Nanotubes, Carbon / Q000737:chemistry*; D009994:Osmolar Concentration; D010100:Oxygen / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D013499:Surface Properties
chemical_list: D037742:Nanotubes, Carbon; D006046:Gold; D012822:Silicon Dioxide; D010100:Oxygen