Blob Size Controls Diffusion of Free Polymer in a Chemically Identical Brush in Semidilute Solution

Zhenyu J Zhang; Steve Edmondson; Matthew Mears; Jeppe Madsen; Steven P Armes; Graham J Leggett; Mark Geoghegan

doi:10.1021/acs.macromol.8b01193

Blob Size Controls Diffusion of Free Polymer in a Chemically Identical Brush in Semidilute Solution

Macromolecules. 2018 Aug 28;51(16):6312-6317. doi: 10.1021/acs.macromol.8b01193. Epub 2018 Aug 10.

Authors

Zhenyu J Zhang^{1

2}, Steve Edmondson³, Matthew Mears¹, Jeppe Madsen⁴, Steven P Armes⁴, Graham J Leggett⁴, Mark Geoghegan¹

Affiliations

¹ Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, U.K.
² School of Chemical Engineering, University of Birmingham, Birmingham B15 2TT, U.K.
³ School of Materials, University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
⁴ Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K.

Abstract

The diffusion of rhodamine-labeled poly(ethylene glycol) (r-PEG) within surface-grafted poly(ethylene glycol) (s-PEG) layers in aqueous solution at 18 °C was measured by fluorescence correlation spectroscopy. The diffusion coefficient of r-PEG within s-PEG was controlled by the grafting density, σ, and scaled as σ^-1.42±0.09. It is proposed that a characteristic blob size associated with the grafted (brush) layer defines the region through which the r-PEG diffusion occurs. The diffusion coefficients for r-PEG in semidilute solution were found to be similar to those in the brushes.