Prediction\nof Surface Segregation of Fluorinated Additives\nfrom Measurement of Wettability Properties of Polymer-Based Blends

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