Microscopic structure and elasticity of weakly aggregated colloidal gels.
We directly probe the microscopic structure, connectivity, and elasticity of colloidal gels using confocal microscopy. We show that the gel is a random network of one-dimensional chains of particles. By measuring thermal fluctuations, we determine the effective spring constant between pairs of particles as a function of separation; this is in agreement with the theory for fractal chains. Long-range attractions between particles lead to freely rotating bonds, and the gel is stabilized by multiple connections among the chains. By contrast, short-range attractions lead to bonds that resist bending, with dramatically suppressed formation of loops of particles.
Dinsmore
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Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA.
Prasad
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Wong
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Weitz
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