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_KWW), as well as β_KWW and Kirkwood correlation factor (g_K), or deviation degree from Arrhenius behavior of structural relaxation times quantified by dynamic fragility (m_P). 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, g_K much below unity, and enormous acceleration of structural relaxation times and viscosity at T = T_g + 20 K. All these peculiarities reveal a strong effect of molecular self-assembly on the dynamics of glass-forming systems.