The Effect of Substrate on Thermodynamic and Kinetic Anisotropies in Alkane Nanofilms

Glasses have a wide range of interesting technological applications, and are preferred over crystalline solids in my applications due to their structural uniformity. The recent discovery of vapor-deposited ultrastable glasses [1] has sparked a renewed interest in the effect of confinement on physicochemical properties of glassy films. In our earlier study [2], we demonstrated that a substrate can induce dynamical acceleration in an atomic liquid film that lies in its vicinity. This dynamic acceleration occurs in the subsurface of the solid-liquid interface, and is different from the previously known dynamical acceleration near the vapor-liquid interface. We attributed this dynamical acceleration to tensile lateral stress fields that are induced by the substrate in the subsurface region of the thin film. In this work, we investigate the effect of a substrate on a molecular nano-film comprised of n-alkane chains. Here, we not only investigate the possibility of substrate-induced dynamical acceleration in molecular films of flexible molecules, but we also study the effect of substrate on rotational relaxation of molecules across the molecular film.  

[1] Swallen, Kearns, et al., Science 315, 353 (2007).

[2] Haji-Akbari, Debenedetti, arXiv:1404.4092.