Study of optical properties of potassium permanganate ( $$\hbox {KMnO}₄$$ KMnO 4 ) doped poly(methylmethacrylate) (PMMA) composite films

We have developed films of pure polymethylmethacrylate (PMMA) (0.5, 1, 2 and 5%) and potassium permanganate $$(\hbox {KMnO}₄)$$ -doped PMMA composite films of thickness ( $$\sim 100\, \upmu \hbox {m}$$ ) using the solution-cast technique. To identify the possible change that happen to the PMMA films due to doping, the optical properties were investigated for different concentrations of $$\hbox {KMnO}₄$$ by recording the absorbance (A) and transmittance ( $$T\%$$ ) spectra of these films using UV–Vis spectrophotometer in the wavelength range of 300–1100 nm. From the data obtained from the optical parameters viz. absorption coefficient ( $$\alpha $$ ), extinction coefficient ( $$\kappa $$ ), finesse coefficient (F), refractive index ( $$\eta $$ ), real and imaginary parts of dielectric constant ( $$\varepsilon _{\mathrm{r}}$$ and $$\varepsilon _{\mathrm{i}})$$ and optical conductivity ( $$\sigma $$ ) were calculated for the prepared films. The indirect optical band gap for the pure and the doped-PMMA films were also estimated.