ABSTRACT:The wettability and surface energy of extruded ULTEM poly(ether imide) films strongly increased (the water contact angle varied from 75 to 38°and the surface energy varied from 45.3 to 59.5 mJ m Ϫ2 , respectively) with the deposition of an allylamine-plasma-polymerized layer and were characterized with X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy according to the experimental parameters. Pervaporation tests for dehydrating the water/ethanol azeotropic mixture were performed at 40°C with nontreated and plasma-treated ULTEM films for 15, 30, 60, and 120 min. No significant difference was noticed in the total flow (ca. 2.5 g/m 2 h) among the various films. However, for the 30-min duration, a great increase in the water selectivity from 850 to 10,850 was measured, and it was related to the higher N/C ratio and the presence of amide groups on the surface.

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Ultem 1000 polyetherimide films prepared by cast-evaporating technique were covered with a 1H,1H,2H-tridecafluoro-oct-1-ene (PFO) plasma-polymerized layer. The effects of the plasma exposure time on the surface composition were studied by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and surface energy analysis. The surface topography of the plasma layer was deduced from scanning electron microscopy. The F/C ratio for plasma-polymerized PFO under the input RF power of 50 W can be as high as 1.30 for 480 s and ϳ0.4 -2 at % of oxygen was detected, resulting from the reaction of long-lived radicals in the plasma polymer with atmospheric oxygen. The plasma deposition of fluorocarbon coating from plasma PFO reduces the surface energy from 46 to 18.3 mJ m Ϫ2.

Step polymerization of bisphenol-A diphthalic anhydride (BAPA) with various mixtures from m-phenylene diamine (m-PDA) and 2-(perfluorohexylmethyl)butan-1,4-diamine (TFD) led to hydrophobic copolyetherimides bearing R F = -CH 2 -C 6 F 13 side chains that were characterized by NMR, elementary analysis, DSC, TGA and surface energy analysis. By increasing the TFD unit%, the glass transition temperature (T g ) decreases according to the Fox equation from 217 8C (m-PDA 100% and TFD 0% like in ULTEM TM 1000) to 113 8C (m-PDA 0% and TFD 100%). Similarly, the surface energy (g s ) decreases from 45.3 mJ m À2 to 27.4 mJ m À2 . The thermal decomposition temperature (T d for 5% weight loss under argon) is slightly affected by introducing TFD units compared with T d for ULTEM TM and it is close to 400 8C. The best compromise between thermal stability, hydrophobic and organophilic properties as well as the ability to form a soft nonporous film by the cast-evaporating method led us to select the copolyetherimide with m-PDA 25% and TFD 75% for which T g = 121 8C, T d = 400 8C and g s = 30.8 mJ m À2 . # 2005 Published by Elsevier B.V.