11 January, 2010
Colloidal glasses and other glassy states in soft materials
Abstract
I will focus on recent developments in the theoretical, numerical and experimental study of slow dynamics in colloidal systems, approaching a glass and/or a gel transition. Colloidal systems appear to be particularly suited for tackling the general problem of dynamic arrest, since they show a larger flexibility compared to atomic and molecular glasses, because of their size and the possibility of manipulating the physical and chemical properties of the samples. Indeed, a wealth of new effects, not easily observable in molecular liquids, have been predicted and measured in colloidal systems[1,2]. I will discuss the slow dynamic behavior of three classes of colloidal suspension: hard colloids, short-range attractive colloids[3] and soft colloidal systems[4], selecting the model systems among the most prominent candidates for grasping the essential features of dynamic arrest. Concerning arrested gel states, I will discuss different routes to gelation which have received particular attention in the last years: phase-separation driven gelation[5], competing interactions[6] and valence reduction[7]. I will stress the importance of understanding the system's kinetic arrest phase diagram, i.e. the regions in phase space where disordered arrested states can be expected.
References and suggested reading
- F. Sciortino and P. Tartaglia Glassy colloidal systems Advances in Physics 54, 471-524, (2005)
- E. Zaccarelli Colloidal Gels: Equilibrium and Non-Equilibrium Routes J. Phys.: Condens. Matter 19, 323101 (2007)
- K. Dawson et al Higher order glass-transition singularities in colloidal systems with attractive singularities Phys. Rev. E 63, 011401, (2001)
- C. Mayer et al Asymmetric caging in soft colloidal mixtures Nature Materials 7, 780 -784 (2008).
- Peter J. Lu et al Gelation of particles with short-range attraction Nature, 453, 499 - 503 (2008).
- Toledano JCF et alColloidal systems with competing interactions: from an arrested repulsive cluster phase to a gel Soft Matter 5, 2390-2398 (2009)
- E. Bianchi et al Phase diagram of patchy colloids: towards empty liquids Phys. Rev. Lett. 97, 168301, 2006.;
Shibu Saw et al, Structural Relaxation of a Gel modeled by Three body interactions, Phys. Rev. Lett. 103, 248305 (2009)