Diffusion-Localization and Liquid-Glass Transitions of a Colloidal Fluid in Porous Confinement

1. Introduction The properties of fluids adsorbed in porous media are of great interest for both technological applications and fundamental science. The effect of the confining matrix on the behaviour of the adsorbed fluid has been studied intensively during the last years both theoretically and in experiments [1]. It was only very recently, however, that a reliable theoretical framework, based on Mode Coupling Theory (MCT), was developed to study the dynamics of fluids in porous confinement [2]. Thus it is now possible to make quantitative predictions about the dynamical properties of simple model systems [2] and possibly more complicated interactions and matrix configurations. The growing interest in soft matter in general and in colloidal systems in particular, motivates the study of the properties of colloidal fluids brought in contact with a soft porous matrix. The study of soft matter in confinement also has two more major advantages: First, the large size of the particles in colloidal suspensions allows direct imaging of the system through video and confocal microscopy, including tracking trajectories of particles [3]. Moreover, optical tweezers allow to fix particles at arbitrary positions, thus providing means to realize suitable matrix configurations. Second, theoretical modelling of complex macromolecular systems through effective potentials is meanwhile rather well established [4]. Hence, colloidal fluids in porous confinement offer an exciting opportunity to make direct contact between theory and experiments.