Bulk glass-formers

Concerning confined polymers exhibiting slowing-down of both the equilibrium and the out-of-equilibrium dynamics, the obvious conclusion is that there exists full interdependence between the two aspects of glassy dynamics in confinement. This agrees with findings on bulk glass former, which, as shown by several studies, display the same interdependence [20, 41, 74, 87, 153, 163, 180]. 

The critical analysis of recently published experimental results allows concluding that, dififerentiy firom bulk glass formers [41, 74, 86, 180], the equilibrium and out-of-equilibrium dynamics are decoupled in confinement [16, 23]. In other words, it is not possible to describe the Tg and the kinetics of equilibrium recovery... 

Zheng Q, Cheng S, Strader JH, Ma E, Xu J, Critical size and strength of the best bulk metallic glass former in the Mg-Cu-Gd ternary system , Scripta Materialia,... 

Daley, C.R., Fakhraai, Z., Ediger, M.D., Forrest, J.A. Comparing surface and bulk flow of a molecular glass former. Soft Matter 8(7), 2206-2212 (2012)... 

Ngai, K.L. Interpreting the dynamics of nano-confined glass-formers and thin polymer films importance of starting from a viable theory for the bulk. J. Polym. Sci. Part B Polym. Phys. 44, 2980 (2006)... 

Reports on the rate of spontaneous fluctuations in confinement are relatively recent. With regards to thin polymer films, pioneering studies in this sense have been performed by broadband dielectric spectroscopy (BDS) on Al-capped thin PS films more than one decade ago by Fukao and Miyamoto [60]. This technique probes the reorientation of dipoles under the application of electric fields in the linear regime [88], and therefore is ideal to characterize the intrinsic molecular mobility in glass formers. Fukao and Miyamoto found that the typical relaxation time remains bulk-like down to thicknesses of 20 nm. For smaller thicknesses, acceleration of the rate of spontaneous fluctuations was observed. Similar results were later reported by others [73, 165]. 

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