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Blob Size Controls Diffusion of Free Polymer in a Chemically Identical Brush in Semidilute Solution
- Zhang, Zhenyu J., Edmondson, Steve, Mears, Matthew, Madsen, Jeppe, Armes, Steven P., Leggett, Graham J., Geoghegan, Mark
- Macromolecules 2018 v.51 no.16 pp. 6312-6317
- aqueous solutions, diffusivity, fluorescence correlation spectroscopy, polyethylene glycol
- 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.