Colloidal dynamics in polymer solutions: Optical two-point microrheology measurements
Abstract
We present an extension of the two-point optical microrheology technique introduced by Crocker \textit{et al.} [Phys. Rev. Lett. \textbf{85}, 888 (2000)] to high frequencies. The correlated fluctuations of two probe spheres held by a pair of optical tweezers within a viscoelastic medium are determined using optical interferometry. A theoretical model is developed to yield the frequency-dependent one- and two-particle response functions from the correlated motion. We demonstrate the validity of this method by determining the one- and two-particle correlations in a semi-dilute solution of polystyrene in decalin. We find that the ratio of the one- and two-particle response functions is anomalous which we interpret as evidence for a slip boundary condition caused by depletion of polymer from the surface of the particle.
Cite
@article{arxiv.cond-mat/0205309,
title = {Colloidal dynamics in polymer solutions: Optical two-point microrheology measurements},
author = {Laura Starrs and Paul Bartlett},
journal= {arXiv preprint arXiv:cond-mat/0205309},
year = {2015}
}