Phys Rev E Stat Nonlin Soft Matter Phys. 2002 May;65(5):051505. doi: 10.1103/PhysRevE.65.051505. Epub 2002 May 20.

Microrheology of polyethylene oxide using diffusing wave spectroscopy and single scattering.

Physical review. E, Statistical, nonlinear, and soft matter physics

Bivash R Dasgupta, Shang-You Tee, John C Crocker, B J Frisken, D A Weitz

PMID: 12059562 DOI: 10.1103/PhysRevE.65.051505

Abstract

Experiments investigating the local viscoelastic properties of a simple uncross-linked flexible polymer are performed on polyethylene oxide solutions in the semidilute regime using polystyrene beads of varying sizes and surface chemistry as probes. We measure the thermal motions of the beads to obtain the elastic and viscous moduli of our sample. Two different dynamic light scattering techniques, diffusing wave spectroscopy and quasielastic light scattering (QELS), are used to determine the dynamics of the probe particles. Diffusing wave spectroscopy probes the short time dynamics of the scatterers while QELS or single scattering measures the dynamics at larger times. This results in a larger frequency overlap of the data obtained from the microrheological techniques with the data obtained from the conventional bulk measurements. The moduli are estimated using a modified algebraic form of the generalized Stokes-Einstein equation. Comparison of microrheology with bulk measurements shows excellent similarity confirming the applicability of this method for simple, uncross-linked polymeric systems.

Publication Types

• Journal Article