ME/ChemE Seminar on "Dynamic Arrest and Aging in Colloidal Systems"

Wednesday, March 31, 2010 - 2:00pm to 3:00pm
Engineering II, room 3519

Speaker: 

Professor Magdaleno Noyola, Universidad Autonomico de San Luis Potosi, Instituto de Fisica, Mexico
Abstract:  The predictions of the self-consistent generalized Langevin equation (SCGLE) theory of dynamic arrest [1] and its very recent non-equilibrium extension to describe aging phenomena are discussed in the context of model colloidal systems. In particular we discuss the glass-fluid-glass  reentrance in monocomponent systems with attractive interactions and in asymmetric hard sphere mixtures, including the Asakura-Oosawa model mixture. We find that the theoretical predictions [2] agree with the experimental glass transition phase diagram of colloid-polymer mixtures [3] and yield a richer and unexpected dynamic arrest scenario. At low colloid concentration, the attractive glass transition meets the spinodal region of the liquid-liquid demixing transition; in this low coloid volume fraction regime the dynamic arrest transition is found to be intimately related with the spinodal line, in qualitative agreement with recent experiments on the gel transition in the same colloid-polymer mixtures [4].  This study is extended to electroneutral mixtures of charged hard spheres, the so-called primitive model of ionic and polyelectrolyte solutions and molten salts, for which the theory predicts [5] a correspondingly richer dynamic arrest scenario that includes partially-arrested states that we identify with Wigner glasses and with model solid electrolytes, and totally arrested states at low volume fractions, that we identify with arrested spinodal gels. The non-equilibrium theory is employed to describe the aging effects that follow a sudden quenching of these systems to their dynamically arrested states.
  
[1]. L. Yeomans-Reyna et al., Phys. Rev. E, 76, 041504 (2007); R. Juárez-Maldonado and M. Medina-Noyola, Phys. Rev. E,77, 051503 (2008). 
[2]. R. Juárez-Maldonado and M. Medina-Noyola, Phys. Rev. Lett. 101 267801 (1998).
[3]. K. N. Pham et al., Science, 296, 104 (2002). 
[4]. P. J. Lu et al., Nature, 453, 499 (2008).
[5]. L.E. Sánchez-Díaz, A. Vizcarra-Rendón, and R. Juárez-Maldonado, Phys. Rev. Lett. (in press, 2009).
This work was supported by the Consejo Nacional de Ciencia y Tecnología (CONACYT, México), through grants 84076 and FMSLP-107543.
 

Host: Todd Squires