  The fundamental understanding of friction of liquids on solid surfaces
remains one of the key knowledge gaps in the transport of fluids. While the
standard perspective emphasizes the role of wettability and commensurability,
recent works have unveiled the crucial role of the solid's internal
excitations, whether electronic or phononic, on liquid-solid dissipation. In
this work, we take advantage of the considerable variation of the molecular
timescales of supercooled glycerol under mild change of temperature, in order
to explore how friction depends on the liquid's molecular dynamics. Using a
dedicated tuning-fork-based AFM to measure the hydrodynamic slippage of
glycerol on mica, we report a 2-order of magnitude increase of the slip length
with decreasing temperature by only 30{\deg}C. However the solid-liquid
friction coefficient is found to be a non monotonous function of the fluid
molecular relaxation rate, f{\alpha}, at odd with an expected Arrhenius
behavior. In particular, the linear increase of friction with the liquid
molecular rate measured at high temperature cannot be accounted for by existing
modelling. We show that this unconventional and non-arrhenian friction is
consistent with a contribution of the solid's phonons to the liquid-solid
friction. This dynamical friction opens new perspectives to control
hydrodynamic flows by properly engineering phononic and electronic excitation
spectra in channel walls.
