Improvement of the water selectivity of ULTEM poly(ether imide) pervaporation films by an allylamine-plasma-polymerized layer

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-2, 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/m2 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.