Diffusion of nanoparticles within a semidilute polyelectrolyte solution.
basic_science · Level V
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- Record sourced from PubMed, PMID 31482916.
- Also identified by DOI 10.1039/c9sm01313j.
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Abstract
We studied the diffusion of charged gold nanoparticles within a semidilute solution of weakly charged polyelectrolyte, polyacrylic acid (PAA) of high molecular weight (M<sub>w</sub> = 10<sup>6</sup> g mol<sup>-1</sup>) by using fluorescence correlation spectroscopy (FCS). Nanoparticle size (d) was varied between 5 nm to 40 nm and PAA volume fraction (φ) in water ranged from about 8φ* to 33φ*, where φ* is the overlap volume fraction. The reduced diffusion coefficient - defined as -D/D<sub>o</sub>, where D is the diffusion coefficient in PAA solution and D<sub>o</sub> is that in neat water - has a weak dependence on the particle size. D follows a power law of the form ∼φ<sup>-0.5</sup>, which can be explained by a mean-field hydrodynamic theory in porous medium. Additional, rheology measurements showed a zero shear rate viscosity and shear thinning, which are typical of high molecular weight polyelectrolytes.