Evidence for Enhanced Tracer Diffusion in Densely Packed Interfacial Assemblies of Hairy Nanoparticles

Nearly monodisperse nanoparticle (NP) spheres attached to a nonvolatile ionic liquid surface were tracked by in situ scanning electron microscopy to obtain the tracer diffusion coefficient Dtr as a function of the areal fraction ϕ. The in situ technique resolved both tracer (gold) and background (si...

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Bibliographic Details
Published in:Nano letters 2023-11, Vol.23 (22), p.10383-10390
Main Authors: Fink, Zachary, Kim, Paul Y., Srivastava, Satyam, Ribbe, Alexander E., Hoagland, David A., Russell, Thomas P.
Format: Article
Language:English
Subjects:
colloidal glasses
diffusion coefficient
electron microscopy
ionic liquid
nanoparticles
NANOSCIENCE AND NANOTECHNOLOGY
single particle tracking
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Summary:Nearly monodisperse nanoparticle (NP) spheres attached to a nonvolatile ionic liquid surface were tracked by in situ scanning electron microscopy to obtain the tracer diffusion coefficient Dtr as a function of the areal fraction ϕ. The in situ technique resolved both tracer (gold) and background (silica) particles for ∼1-2 min, highlighting their mechanisms of diffusion, which were strongly dependent on ϕ. Structure and dynamics at low and moderate ϕ paralleled those reported for larger colloidal spheres, showing an increase in order and a decrease in Dtr by over 4 orders of magnitude. However, ligand interactions were more important near jamming, leading to different caging and jamming dynamics for smaller NPs. The normalized Dtr at ultrahigh ϕ depended on particle diameter and ligand molecular weight. Increasing the PEG molecular weight by a factor of 4 increased Dtr by 2 orders of magnitude at ultrahigh ϕ, indicating stronger ligand lubrication for smaller particles.
ISSN:1530-6984
1530-6992
DOI:10.1021/acs.nanolett.3c02989