title: Connecting nanoscale motion and rheology of gel-forming colloidal suspensions.
abstract: We report a combined x-ray photon correlation spectroscopy and rheometry study of moderately concentrated suspensions of silica colloids that form a gel on cooling. During gel formation, the suspensions acquire a shear modulus that increases with time, while the thermal motion of the colloids becomes localized over an increasingly restricted range. The nanometer-scale localization length characterizing this motion obeys an exact relationship with the shear modulus predicted theoretically from mode coupling calculations [K. S. Schweizer and G. Yatsenko, J. Chem. Phys. 127, 164505 (2007)]. This scaling thus demonstrates a direct quantitative connection between the microscopic dynamics and macroscopic rheology. It further indicates the importance of local structure over longer-range correlations in dictating the dynamical and mechanical properties of such gels.
authors.affiliation: Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: Hongyu
authors.initials: H
authors.lastname: Guo
authors.forename: S
authors.initials: S
authors.lastname: Ramakrishnan
authors.forename: James L
authors.initials: JL
authors.lastname: Harden
authors.forename: Robert L
authors.initials: RL
authors.lastname: Leheny
mesh_terms: D001703:Biophysics / Q000379:methods; D003102:Colloids / Q000737:chemistry*; D005782:Gels; D053758:Nanoparticles / Q000737:chemistry; D036103:Nanotechnology / Q000379:methods*; D012212:Rheology / Q000379:methods; D033081:Shear Strength; D013696:Temperature
chemical_list: D003102:Colloids; D005782:Gels