Slow dynamics of a confined supercooled binary mixture in comparison with the bulk phase

摘要

Dynamic properties of a liquid Lennard-Jones binary mixture embedded in an off-lattice matrix of soft spheres and the corresponding bulk phase are studied upon supercooling close to the crossover temperature of mode-coupling theory by molecular dynamics simulations. The model confining system is designed to mimic the properties of silica xerogels. In spite of the strong confinement the dynamic behaviour of the mixture is consistent with the mode-coupling predictions. The parameters of the theory are compared for bulk and confined phases. The range of validity of the theory shrinks in confinement. Consistently with the hypothesis of a growing length scale in supercooled liquids, the dynamics of the confined mixture are faster than those of the equivalent bulk phase.