The aim of this work is to describe the segregation phenomenon
of random perfluorinated copolymers toward the surface of a polystyrene
(PS) matrix. Three random perfluorinated copolymers, named POISE-a
(Polymer prOcessing Interface StabilizEr), synthesized with different
amounts of chemically bound fluorine, were mixed with a commercial
PS matrix by a solvent casting process. Their effect on the wettability
properties of PS as a function of their concentration was measured
first under static conditions with different liquids (water, formamide,
diethylene glycol) and then under dynamic conditions with water. The
evolution of the cosine of the static and dynamic advancing contact
angles as a function of the fluorine content by weight in the bulk
was predicted using an original physical law, in which the different
parameters were related to the morphology of the additivated polymers
as revealed by experimental X-ray photoelectron spectroscopy (XPS)
and scanning electron microscopy-energy dispersive X-ray (SEM-EDX)
measurements. This law has been successfully used to predict the wetting
properties of other polymer blends and has contributed to a better
understanding of the phase segregation mechanism of additives migrating
to the PS surface, at the origin of the increase in hydrophobicity.