Issue 38, 2015

Diffusive dynamics of nanoparticles in ultra-confined media

Abstract

Differential dynamic microscopy (DDM) was used to investigate the diffusive dynamics of nanoparticles of diameter 200–400 nm that were strongly confined in a periodic square array of cylindrical nanoposts. The minimum distance between posts was 1.3–5 times the diameter of the nanoparticles. The image structure functions obtained from the DDM analysis were isotropic and could be fit by a stretched exponential function. The relaxation time scaled diffusively across the range of wave vectors studied, and the corresponding scalar diffusivities decreased monotonically with increased confinement. The decrease in diffusivity could be described by models for hindered diffusion that accounted for steric restrictions and hydrodynamic interactions. The stretching exponent decreased linearly as the nanoparticles were increasingly confined by the posts. Together, these results are consistent with a picture in which strongly confined nanoparticles experience a heterogeneous spatial environment arising from hydrodynamics and volume exclusion on time scales comparable to cage escape, leading to multiple relaxation processes and Fickian but non-Gaussian diffusive dynamics.

Graphical abstract: Diffusive dynamics of nanoparticles in ultra-confined media

Supplementary files

Article information

Article type
Paper
Submitted
10 Jun 2015
Accepted
09 Aug 2015
First published
10 Aug 2015

Soft Matter, 2015,11, 7515-7524

Author version available

Diffusive dynamics of nanoparticles in ultra-confined media

J. D. C. Jacob, K. He, S. T. Retterer, R. Krishnamoorti and J. C. Conrad, Soft Matter, 2015, 11, 7515 DOI: 10.1039/C5SM01437A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements