In this work, we present experimental data on the behavior
of model
additives adsorbed at the solid/liquid interface as a function of
pressure. We report that some additives adsorbed from non-aqueous
solvents exhibit rather little variation with pressure, while others
exhibit more significant changes. We also display the important pressure
dependence of added water. This pressure dependence is relevant, indeed
central to many commercially important situations where the adsorption
of molecular species to the solid/liquid interface under high pressure
is key, such as wind turbines, and this work should help in understanding
how protective, anti-wear, or friction-reducing agents can persist
(or not) under these extreme conditions. With a very significant gap
in the fundamental understanding of the role of pressure on adsorption
from solution phases, this important fundamental study provides a
methodology to investigate the pressure dependence of these academically
and commercially important systems. In the best case, one may even
be able to predict which additives will lead to more adsorption under
pressure and avoid those that may desorb.