Evidence for Enhanced Tracer Diffusion in Densely Packed Interfacial Assemblies of Hairy Nanoparticles.
basic_science · Level V
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- Record sourced from PubMed, PMID 37955362.
- Also identified by DOI 10.1021/acs.nanolett.3c02989.
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Abstract
Nearly monodisperse nanoparticle (NP) spheres attached to a nonvolatile ionic liquid surface were tracked by <i>in situ</i> scanning electron microscopy to obtain the tracer diffusion coefficient <i>D</i><sub><i>tr</i></sub> as a function of the areal fraction ϕ. The <i>in situ</i> 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 <i>D</i><sub><i>tr</i></sub> 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 <i>D</i><sub><i>tr</i></sub> at ultrahigh ϕ depended on particle diameter and ligand molecular weight. Increasing the PEG molecular weight by a factor of 4 increased <i>D</i><sub><i>tr</i></sub> by 2 orders of magnitude at ultrahigh ϕ, indicating stronger ligand lubrication for smaller particles.