Surface Characteristics of Polystyrene Fluoroalkylated with Perfluoroalkanoyl Peroxides (3)

Abstract

Perfluoro-oxa-alkylated polystyrenes (PSt-CF (CF₃) O {CF₂CF (CF₃) O} _mC₃F₇; m=0,1,2) having various fluoro-oxa-alkylated ratio (Rf ratio) films were prepared using various perfluoro-oxa-alkanoyl peroxides (Rf (CO) OO (CO) Rf ; Rf=CF (CF₃) O{CF₂CF(CF₃)O}_mC₃F₇, m=0.1, 2). The surface characteristics of the polystyrene films were studied by contact angle measurement and X-ray photoelectron spectroscopy (XPS). Critical surface tension (γ_c) of polystyrene films decreased with an increase in Rf ratio in the beginning, and then remained constant above a certain Rf ratio (above 13% in m=1). γ_c also decreased with the increase in the number of carbon, m. XPS analysis revealed that surface fluorine concentration increased in the beginning with the increase of Rf ratio and was saturated at the same Rf ratio (13% in m=1). The surface fluorine concentration was found to increase with increasing number of carbon, m. It was found that a great amount of CF₃ functional groups were present on the surface of improved polystyrenes, which showed lower γ_c, compared with perfluoroalkylated polystyrene (PSt-C_nF_2n+1; n=3, 6, 7).