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.