SURFACE-PROPERTIES OF POLYMERS TREATED WITH TETRAFLUOROMETHANE PLASMA

Polymer films of poly(ethylene terephthalate), polypropylene, and cell ophane were surface treated with tetrafluoromethane plasma under diffe rent time, power, and pressure conditions. Contact angles for water an d methylene iodide and surface energy were analyzed with a dynamic con tact angle analyzer. The stability of the treated surfaces was investi gated by washing them with water or acetone, followed by contact angle measurements. The plasma treatments decreased the surface energies to 2-20 mJ/m(2) and consequently enhanced the hydrophobicity and oleopho bicity of the materials. The treated surfaces were only moderately aff ected after washing with water and acetone, indicating stable surface treatments. The chemical composition of the material surfaces was anal yzed with X-ray photoelectron spectroscopy (XPS) and revealed the inco rporation of about 35-60 atomic % fluorine atoms in the surfaces after the treatments. The relative chemical composition of the C Is spectra 's showed the incorporation of -CHF- groups and highly nonpolar -CF2- and -CF3 groups in the surfaces and also -(C) under bar H-2-CF2- group s in the surface of polypropylene. The hydrophobicity and oleophobicit y improved with increased content of nonpolar -CF2-, -CF3, and -(C) un der bar H-2-CF2- groups in the surfaces. For polyester and polypropyle ne, all major changes in chemical composition, advancing contact angle , and surface energy are attained after plasma treatment for one minut e, while longer treatment time is required for cellophane. (C) 1997 Jo hn Wiley & Sons, Inc.