Conversion of Hydrophilic Surface of Poly(ethylene terephthalate) Film to Hydrophobic One under Hydrophilic Conditions

Yasuyuki SUZUKI, Jun LI, Yasunari MAEKAWA*, Masaru YOSHIDA, Katsuya MAEYAMA and Noriyuki YONEZAWA

Department of Material Development, Takasaki Radiation Chemistry Research Establishment, Japan Atomic Energy Research Institute; 1233 Watanuki, Takasaki-shi 370-1292 Japan
Department of Organic and Polymer Materials Chemistry, Tokyo University of Agriculture and Technology; 2-24-16 Naka-machi, Koganei-shi 184-8588 Japan

The hydrophilic surface of poly (ethylene terephthalate) (PET) film, obtained by partial hydrolysis, was converted to hydrophobic one under dry air, saturated water vapor atmosphere, nitrogen, and vacuum at temperatures ranging from 0 to 80 °C. The hydrophilicity of the surface increased significantly faster under the saturated water vapor although it was the most hydrophilic in the examined conditions. From the dependence of the absolute temperature on the rate of hydrophilicity change for each storage condition, a discontinuous point at ca. 50 °C was observable only under the water vapor condition. This relation indicates that the appreciable acceleration of the hydrophilicity change on the surface under the hydrophilic condition might be resulted from the increase of the surface mobility due to the water adsorption on the PET surface.

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