### Session Q8: Colloidal Phase Behavior

11:15 AM–2:15 PM, Wednesday, March 12, 2008
Morial Convention Center Room: RO6

Chair: Jerzy Blawzdziewicz, Yale University

Abstract ID: BAPS.2008.MAR.Q8.14

### Abstract: Q8.00014 : Correlations between Dynamical Heterogeneities and Visco-elastic properties of Confined Colloidal Thin Films

1:51 PM–2:03 PM

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#### Authors:

Our recent study on confined hard-sphere colloidal suspensions demonstrates that glass transition can be observed sooner' as film thickness approaches a critical value while volume fraction remains constant. In this talk, we present a new study of the rheological properties of strongly confined colloidal thin films by using a home-designed micro-rheometer interfaced with a confocal microscope. We visualize the shear-induced structural relaxation at a single particle level and measure the rheological properties of confined colloidal thin films between two surfaces at narrow gap spacing ranging from 50 $\mu$m to 1-2 $\mu$m. The application of shear excitation greatly accelerates structural relaxation compared to quiescent colloidal fluids and we visualize particle displacements during the `bond breakage'' process in strongly confined thin films. Additionally, we characterize their patterns, size and lifetimes under varied shear rates, and correlate their behaviors to the measured visco-elastic and visco-plastic properties of confined colloidal thin films.