Abstract

We use multispeckle dynamic light scattering to measure the dynamic structure factor, f (q, τ), of gels formed by aggregation of colloids. Although the gel is an elastic solid, f (q, τ) nearly completely decays on long time scales, with an unusual form, f (q, τ) ∼ exp{-(τ / τ f)μ}, with μ ≈ 1.5 and with τ f ∝ q -1. A model for restructuring of the gel with aging correctly accounts for this behavior. Aging leads to a dramatic increase in τ f; however, all data can be scaled on a single master curve, with τ f asymptotically growing linearly with age. This behavior is strikingly similar to that predicted for aging in disordered glassy systems, offering convincing proof of the universality of these concepts.

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