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Download fileLocal Confinement Controls Diffusive Nanoparticle Dynamics in Semidilute Polyelectrolyte Solutions
journal contribution
posted on 30.07.2020, 22:03 authored by Ali H. Slim, Ryan Poling-Skutvik, Jacinta C. ConradWe
investigate the mobility of polystyrene particles ranging from
100 to 790 nm in diameter in dilute and semidilute sodium polystyrene
sulfonate (NaPSS) solutions using fluorescence microscopy. We tune
the polymer conformations by varying the ionic strength of the solution.
The nanoparticle mean-squared displacements evolve linearly with time
at all time scales, indicating Fickian diffusive dynamics. In solutions
of high ionic strength, chains adopt a random walk conformation and
particle dynamics couple to the bulk zero-shear rate viscosity, according
to the Stokes–Einstein picture. In solutions of low ionic strength,
however, particle dynamics nonmonotonically deviate from bulk predictions
as polymer concentration increases and are not accurately predicted
by the available models. These nonmonotonic dynamics directly correlate
with the non-Gaussianity in distributions of particle displacements,
suggesting the emergence of a local confining length scale as polyelectrolyte
concentration increases.
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Keywords
Semidilute Polyelectrolyte Solutionsparticle displacementsparticle dynamics nonmonotonicallyFickian diffusive dynamicsstrengthpolyelectrolyte concentration increasesbulk zero-shear rate viscositypolystyrene particlesbulk predictionsnonmonotonic dynamicsLocal Confinement Controls Diffusiv...fluorescence microscopypolymer concentration increasessolutionparticle dynamics couple790 nmlength scalenanoparticle mean-squared displacementstime scalessemidilute sodium polystyrene sulfonatepolymer conformations