were poured into Petri dishes (internal
diameter 9 cm; Deltalab, Spain) and dried at 60 C to
evaporate the acetic acid. The resulting films were then
neutralized with 4 wt% NaOH solution and thoroughly
washed with distilled deionized-water [36] (until reaching
neutrality). The films were then dried in the furnace at 60 C,
and stored in the dark for further use.