Effect of Lithium Salts on the Optical Properties of Poly Acrylonitrile/Poly Methyl Methacrylate Blends

Polymer blends from Poly Acrylonitrile/Poly Methyl Methacrylate (PAN/PMMA) with different blend ratios (80/20, 75/25,70/30,65/35, and 60/40) wt% undoped and doped with various lithium (Li) salts (LiCO3, Li2SO4H2O, and LiCl) at 20 wt %. Different techniques were employed to investigate the composition and optical properties of the prepared blend samples undoped and doped with Lithium salts like FT-IR and UV-Visible spectroscopies. The optical properties analysis declared that the energy gap increased from (4.0 eV to 4.20 eV) by increasing of PMMA ratio from 20 to 40 wt %. In contrast, the energy gap reduced and shifted toward the low energy side by adding lithium salts; the minimum energy gap value was 2 eV obtained from 65 % PAN and 35 % PMMA doped with Li2CO3. The optical constants were determined and plotted as a function of wavelength in the range (of 100-1100) nm. The general results showed that the optical constants (n, εr, and εi) for undoped blends increased with the PMMA ratio from 20 to 35 wt%. In contrast, all-optical constants were grown with the addition of lithium salts.