title: Microscopic structure and elasticity of weakly aggregated colloidal gels.
abstract: 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.
authors.affiliation: Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA.
authors.forename: A D
authors.initials: AD
authors.lastname: Dinsmore
authors.forename: V
authors.initials: V
authors.lastname: Prasad
authors.forename: I Y
authors.initials: IY
authors.lastname: Wong
authors.forename: D A
authors.initials: DA
authors.lastname: Weitz