Impact of the Interfacial Energy and Density Fluctuations on the Shift of the Glass-Transition Temperature of Liquids Confined in Pores

The behavior of the low- and high-molecular weight glass formers confined in nanoporous templates remains an unsolved puzzle despite the intensive long-term studies in this matter. Special effort is taken to understand the enhancement of segmental or structural dynamics and the depression of the glass-transition temperatures, Tgs in materials infiltrated in pores of the nanometric size. In this paper, we have analyzed dielectric, calorimetric, and contact angle data collected for various systems to determine which factors are responsible for these effects. It turned out that with increasing interfacial energy, molecules attached to the pore walls (interfacial layer) vitrify at higher temperatures. Moreover, the dynamics of core molecules starts to deviate from bulk-like behavior. Therefore, a greater depression of the glass-transition temperature, Tg, of this fraction of molecules is noted. Also, it was found that the sensitivity of structural dynamics to the density fluctuations, quantified by the pressu...