Fluorine-Assisted Self-Assembly Triggers Peculiarities in Molecular Dynamics of a Polar Glass-Former.

Condensed matter physics has long struggled to obtain a comprehensive picture of the liquid-glass transition. Consequently, over the years, universal manifestations of glassy and supercooled dynamics have been established, including a correlation between the static dielectric constant (Δε) and relaxation stretching (β), as well as β and Kirkwood correlation factor (), or deviation degree from Arrhenius behavior of structural relaxation times quantified by dynamic fragility (). Herein, we report a simple, highly polar liquid that breaks all of these rules established for glass-forming liquids. We show that the fluorine-assisted self-assembly, confirmed by temperature-dependent Raman and XRD measurements, brings peculiarities in relaxation dynamics, that is, extremely low dielectric strength, Debye-like shape of dielectric permittivity spectra, much below unity, and enormous acceleration of structural relaxation times and viscosity at = + 20 K. All these peculiarities reveal a strong effect of molecular self-assembly on the dynamics of glass-forming systems.