*2.3. Color*

Color was determined using a portable spectrophotometer (Mini Scan EZ 4500L, HunterLab, Reston, VA, USA) based on the CIELab scale with the coordinates *L\**, *a\**, and *b\** [18]. The films were placed on a white copy paper used as standard with color coordinate values of *L\** = 91.76, *a\** = 2.14, and *b\** = −10.64.
