by spring clips. The assembly was fully cured into a thermostated oven (TERMAKS, B8000 series, mod. B8054) held at several curing temperatures 25, 50, 75 or 100 ± 1◦C for certain time periods:9 days, 3 days, 23 h and 6 h correspondingly, specified by our previous work [6]. When polymerization was over, the film samples were carefully removed, material excess-free, and stored in dark place at room temperature.