Fri, 25 Jul 2008 04:37:27 BST CiteULike: dchens Farouji http://www.citeulike.org/user/dchen/author/Farouji CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dchen/article/2795389 <i>Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 71, No. 2. (2005)</i><br /><br />There are two types of isotropic disordered nonergodic states in colloidal suspensions: colloidal glasses and gels. In a recent paper [H. Tanaka, J. Meunier, and D. Bonn, Phys. Rev. E 69, 031404 (2004)], we discussed the static aspect of the differences and the similarities between the two. In this paper, we focus on the dynamic aspect. The kinetics of the liquid-glass transition is called "aging," while that of the sol-gel transition is called "gelation." The former is primarily governed by repulsive interactions between particles, while the latter is dominated by attractive interactions. Slowing down of the dynamics during aging reflects the increasing cooperativity required for the escape of a particle from the cage formed by the surrounding particles, while that during gelation reflects the increase in the size of particle clusters towards the percolation transition. Despite these clear differences in the origin of the slowing down of the kinetics between the two, it is not straightforward experimentally to distinguish them in a clear manner. For an understanding of the universal nature of ergodic-to-nonergodic transitions, it is of fundamental importance to elucidate the differences and the similarities in the kinetics between aging and gelation. We consider this problem, taking Laponite suspension as an explicit example. In particular, we focus on the two types of nonergodic states: (i) an attractive gel formed by van der Waals attractions for high ionic strengths and (ii) a repulsive Wigner glass stabilized by long-range Coulomb repulsions for low ionic strengths. We demonstrate that the aging of colloidal Wigner glass crucially differs not only from gelation, but also from the aging of structural and spin glasses. The aging of the colloidal Wigner glass is characterized by the unique cage-forming regime that does not exist in the aging of spin and structural glasses. Kinetics of ergodic-to-nonergodic transitions in charged colloidal suspensions: Aging and gelation Hajime Tanaka Sara Farouji Jacques Meunier Daniel Bonn doi:10.1103/PhysRevE.71.021402 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 71, No. 2. (2005) 2008-05-13T15:20:47-00:00 2005 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics) 71 2 APS aging gel simulation tanaka http://www.citeulike.org/user/dchen/article/1988262 <i>Physical Review Letters, Vol. 98, No. 10. (2007)</i><br /><br />We provide a direct experimental test of the fluctuation-dissipation theorem (FDT) in an aging colloidal glass. The use of combined active and passive microrheology allows us to independently measure both the correlation and response functions in this nonequilibrium situation. Contrary to previous reports, we find no deviations from the FDT over several decades in frequency (1 Hz–10 kHz) and for all aging times. In addition, we find two distinct viscoelastic contributions in the aging glass, including a nearly elastic response at low frequencies that grows during aging. Fluctuation-Dissipation Theorem in an Aging Colloidal Glass Sara Farouji Daisuke Mizuno Maryam Atakhorrami Fred Mackintosh Christoph Schmidt Erika Eiser Gerard Wegdam Daniel Bonn doi:10.1103/PhysRevLett.98.108302 Physical Review Letters, Vol. 98, No. 10. (2007) 2007-11-26T20:20:36-00:00 2007 Physical Review Letters 98 10 APS 2007 aging colloids experiment glass theory