Viscoelasticity of aqueous telechelic poly(ethylene oxide) solutions: relaxation and structure

We present a rheology study of associating polymers. The associating polymers are telechelic, composed of a water-soluble backbone (polyethylene oxide) terminated by hydrophobic moieties (C16H33). In aqueous solutions, these polymers self-assemble to form micellar structures. Above a critical concentration, approximately 1 wt % of polymer, bridging between the micelles forms a transient network. Traditionally, the viscoelastic response of these polymeric solutions has been described using the Maxwell model. In this work we measure the viscoelastic properties over an extended frequency range (0.01-6000 Hz) using microrheology, and show that at high frequencies the rheology behaves as the square root of the oscillation frequency. To fit the data, we use a combination of the Maxwell model and the Rouse model. The Maxwell model accounts for the hydrophobic associations between the polymeric micelles, and the Rouse model accounts for the microscopic dynamics of the individual micelles.