Interfacial effects on the dynamics of cooperatively rearranging regions

Abstract

The glass‐forming liquid 2‐methyltetrahydrofuran is particularly well described by the theory of Adam and Gibbs as regards the coupling between molecular dynamics and configurational entropy near the glass transition temperature at Tg = 91 K. Therefore, the underlying physical picture of cooperatively rearranging regions captures the temperature dependence of orientational dynamics for the bulk liquid on the basis of the configurational entropy. We demonstrate that geometrical confinement of such a liquid to nanopores gives rise to a dynamical coupling of the liquid to the rigid pore wall resulting in a non‐ergodic regime for long time, whereas the short time dynamics remain unaffected.

Some comments on heterogeneity at the glass transition

“…Therefore, one should distinguish regions of cooperative motion from domains defined by spatial heterogeneity. The question of whether a correlation length ξ of cooperative motion can be identified via experiments in systems with geometrical confinements of size d ∼ ξ has still not been answered unambiguously [20,21]. Even a confinement which is neither wetting nor dewetting the confined liquid may not be appropriate for identifying the cooperative length ξ .…”